LGA 1150 Haswell Motherboard with proper VT-d support

[zir_blazer]

TweakTown played a bit with the X10SAT, though they didn't did anything new or reelevant with it.

I already paid the reserve value for the Xeon and the X10SAT. I should have it next week. Had to break the piggy bank. Years ago I didn't even bother to think on the possibility of purchasing high end parts like these.



I'm still dissapointed that Supermicro doesn't want to make X10SAT a hybrid Workstation and enthusiast Motherboard, because it could fill both roles nicely. All it should take would be a BIOS upgrade to make me happy.
As far that I am aware, the only thing that you can do on a Z87 Chipset that you can't in a C226 is to be able to freely change the CPU Multiplier on the ones that have it Unlocked. Assuming that is true, you can still do things like overclocking Haswell GPU on the other Chipsets, and I suppose that you could use a lower-than-default CPU Multiplier if you wanted to underclock. But considering that I want VT-d and K series Processors doesn't have it, missing that single feature from Z87 doesn't matter, as it seems that it could have everything else.

 

[WOTMODS]

...

B75/B85/x79 such as Asus supports vt-d as well as the Q series

Having Asus Bx5, Q and x79 ESXi lab boxes they work similarly passing such devices as SB sound cards through...

The trick with vt-d in such platforms as ESXi is where and how your device is connected - i.e.) pass a PCI sound card you're passing all of that hw therefore if you have NIC for example on the same it cannot be disassociated with the the device you desire to pass through...

Built-in HW such as realtek NICs, sound etc. are flaky at best in passthrough

For success a discreet vga / Intel NIC / SB sound etc. is highly recommended and on different buses depending on how and what you want to pass (PCI Sound / PCIe NIC etc.)...

Use PS2 converter or native PS2 keyboard on Haswell for ESXi 5.5 and below, Windows 2008 R2 install etc.

Anything less than ESXi 5.1 Haswell will be agony

Set secure boot off if you find Haswell still can't boot trying such scenarios as disabling uefi boot / CSM depending on mobo will force a rediscovery and it will boot

Honestly at this point I would steer away from Haswell for anything but Windows 7SP1 and up or something equivalent to Fedora 19 and up... You're fun experience will be significantly higher sticking with IVB/SB and associated cxxx/Q/B or x79 chipsets for virtualization...

 

[fabg]

Hello all, I am new in the forum, it called my attention the original post from Zyr Blazer sometime ago. At this point I do not know if all the questions got a proper answer. I am in the process of building a training lab server and after much research arrived to these conclusions:

1. It appears all manufacturers are pushing virtualization
2. Intel i7 family could be used for virtualization with the Chipset Z87
3. Intel Xeon E3 family could be used with Chipset C226
4. In both cases you need a 1150 based motherboard, the BIOS is a given
5. Only Xeon E series with Chipset C226 is server oriented

Intel introduced the Xeon E3 family as alternatives for low costs servers for small business, it appears the best solution for my purpose. My server will be Windows based using Hyper-V running multiple win and Linux OSs

It appears at this time motherboard manufacturers do not offer many options for Xeon E3 + C226. Has anyone found new motherboards filling this niche? I will use the Xeon E3 1275v3 which offers the best features for my purpose.

My search includes
1. Asus P9D-WS
2. Supermicro MBD-X10SAT-O
3. Gigabyte appears not to have a board for Xeon E3 + C226

I did not find meaningful discussions or reviews in internet about these boards, most of the post offer alternatives requiring to switch to the i7 family with Chipset Z87.

Excuse my long post, seeking and trying to provide and useful information.

Thank you. -fab-

If someone already posted an answer would be so kind as to send me a link please?

 

[fabg]

I already paid the reserve value for the Xeon and the X10SAT. I should have it next week. Had to break the piggy bank. Years ago I didn't even bother to think on the possibility of purchasing high end parts like these.

It appears a good combination. Forgot to mention the Asus P9D-WS comes with a 802.11a/c backward compatible wireless adapter. So am looking for something similar. Xeon E31274v3 is comparable to i7 4771, but it accepts ECC memory and has not potential media constrains. May be, not very important in multifunction lab server.

Many discussions are about Raid, but the BIOS supported raid should suffice for lab purposes.

 

[zir_blazer]

2. Intel i7 family could be used for virtualization with the Chipset Z87

It doesn't have to be an Core i7. Most i5 got VT-d. Avoid K series Processors, these got VT-d disabled.

4. In both cases you need a 1150 based motherboard, the BIOS is a given

Manufacturer support for VT-d seems to have drastically improved during the last few months. Still, it may pay off to google around to see if there is people that can get it working, even if you can't find the same model, at least on similar Motherboards from same brand and generation.

It appears at this time motherboard manufacturers do not offer many options for Xeon E3 + C226. Has anyone found new motherboards filling this niche? I will use the Xeon E3 1275v3 which offers the best features for my purpose.

There aren't many C226 Motherboards. Supermicro X10SAT and X10SAE seems to be among the top of the bunch. Other options were AsRock C226 WS and C226 WS+. Personally, I seriously dislike Asus due to their official "we don't support Linux" stance and the fact that they have been the ones with worst track record regarding VT-d and AMD-Vi support.

Additionally, you may want to see if the price difference betwen the E3-1245v3 and 1275v3 is justificable. Its 60 U$D for a mere 100 MHz.





I'm using the Xeon and the X10SAT from around three weeks ago, additionally I purchased a Seagate Desktop HDD.15 4 TB Hard Disk to go with it, however, I wasn't able to do with it what I wanted:

- I managed to install Arch Linux and Xen using legacy BIOS, I did so with Syslinux Boot Loader, as you can install it in BIOS mode and have GPT support. However, after trying most things I had the knowledge to try, I didn't managed to get VGA passthrough working for my Windows XP VM, so no success here.
- After two weeks, I didn't managed to get Xen working in UEFI mode instead of legacy BIOS (Have a Thread about that in Xen Mailing List). I'm bent on getting it to work in UEFI because I don't want to use legacy BIOS - bleeding edge Hardware and still using 40 years old code looks rather lame.
- The Xeon with stock cooling THERMAL THROTTLES. As I knew that Haswell run rather hot and I'm not intending on spending a single cent more than what I did on a bigger heatsink (Piggy bank still in pieces), I was intending to undervolt it to reduce generated heat. I was actually looking for means to do so before purchasing, as I was expecting that to happen.
Supermicro literally forces you to run everything to-spec, so the BIOS doesn't give me any way to reduce Multiplier, Voltage, whatever. Due to several factors that adds in to heat build up, the net result is that my Xeon reachs 100°C and Motherboard speaker goes haywire to report overheat. I have nothing to do but to live with it until this damned summer ends, as there doesn't seem to be possible to undervolt Haswell via Software, worse in Linux that seems to have less tools to tweak Hardware that Windows does.

Overally, I have mixed feelings. After spending a bucketload of money I'm less productive than on my old machine and Windows XP because I couldn't get Xen working (VT-d itself seems to work, but there are also extra patches that must be applied to get the VM to actually see and use the GPU, which looks like I didn't get right), and in Linux is rather limited what I can do of my old gaming activities. And the thermal throttling issue annoys me too, as there is no way to force it to run at less than stock settings. Outside that I don't have control regarding at what settings I want the Hardware to run, the X10SAT left me with a rather good impression as it seems rather solid.

 

[fabg]

Hello Zir_Blazer,

Summer? Where are you?

You are correct, it appears the E3-1275v3 has not advantages over the E3-1245v3 for my lab. Thanks. As for the motherboards, it is back to review specifications until next week, with some luck prices will be lower. The lab asks for multiple NICs and switch, but not wireless (No ASUS) so, I will check again Supermicro X10SAT-O and Asrock C226-WS and pick one.

Do you have any experience with Corsair or some other brand? Always used Kingston and have not complaints, but ECC registered memory is more expensive. Please keep me posted about your build.

Thank you for your response, have a Merry Christmas and a Great 2014.

fab

 

[zir_blazer]

Summer? Where are you?

Argentina. Its summer this side of Earth.

Do you have any experience with Corsair or some other brand? Always used Kingston and have not complaints, but ECC registered memory is more expensive. Please keep me posted about your build.

For RAM on LGA 1150, you can use either standard Unbuffered or Unbuffered/ECC DDR-3 Memory Modules. Buffered (Also called Registered) will NOT WORK, so avoid Buffered or Buffered/ECC on this platform.
I didn't researched about Unbuffered/ECC RAM brands and models because I already had my 32 GB of RAM before doing the switch from a Desktop build to a serious Workstation one. Had I know I was going to be using a Server Processor and Motherboard, I may as well had purchased Unbuffered/ECC RAM for a killer combo. If I recall correctly, it wasn't that much expensive, but variety was limited and you have even less info about ICs, overclocking, etc, on those.

 

[fabg]

It appears Amazon has some Intel PCIe NICs a very good price

http://www.amazon.com/s/ref=sr_nr_p_...nid=6011944011

The training lab am building is Windows server 2012 based, requires four NICs. Linux will be a guest OS. Ordered X10SAT-O to try Thunderbolt and Xeon E3 1275v3 because it has L2 cache and some VT friendly features not available in 1245...or not :whiste:

Thank you.

 

[zir_blazer]

Xeon E3 1275v3 because it has L2 cache and some VT friendly features not available in 1245...or not :whiste:

Its only 100 MHz difference in CPU and 50 MHz in GPU. Feature wise they're exactly the same. I think these 60 U$D could be put to better use in any other component.

 

[fabg]

Argentina. Its summer this side of Earth.

For RAM on LGA 1150, you can use either standard Unbuffered or Unbuffered/ECC DDR-3 Memory Modules. Buffered (Also called Registered) will NOT WORK, so avoid Buffered or Buffered/ECC on this platform..

Hello Zir_Blazer,

You are right, not buffered RAM for this CPU. It appears Buffered is not exactly Registered memory even when they play similar functions.

http://www.servethehome.com/unbuffered-registered-ecc-memory-difference-ecc-udimms-rdimms/

Been only once in Buenos Aires delivering a seminary, have a couple of friends from Mendoza and Malbec is my favorite wine. Where do you live?

fab

 

[fabg]

See your point. I will check specifications again, I can exchange the CPU when it arrives. I am not paying extra for the 100 MHz.

http://www.cpu-world.com/Compare/404/Intel_Xeon_E3-1245_v3_vs_Intel_Xeon_E3-1275_v3.html

Thanks,

fab

 

[zir_blazer]

It appears Buffered is not exactly Registered memory even when they play similar functions.

Buffered and Registered are pretty much synonymous. The only time I ever read them as a different thing was from a FAQ entry that mentioned stuff from the SIMM era, here. But if on a DDR-3 module you see people saying its "Buffered" or "Registered", its the exact same thing.

Been once in Buenos Aires delivering a seminary, have a couple of friends from Mendoza and Malbec is my favorite wine. Where do you live?

I'm from Buenos Aires. I don't drink alcohol - no favorites there.

 

[fabg]

Got it about the memory, I decided on this one: KVR16R11D4/8 x 2 for a total of 16GB, enough for multiple VMs. It is not clear from your posts (The ones I read) if you are building for gaming or also for work.

Is this the proper forum to post about my building experience? I would like to receive some comments as the training lab advances. It is a slow long term project.

Thank you for your assistance.
fab

 

[zir_blazer]

Got it about the memory, I decided on this one: KVR16R11D4/8 x 2

That one is Buffered (Or Registered if you want to call them that. I prefer Buffered). It will not work on LGA 1150.

Pick from this list. They're filtered to be Unbuffered/ECC.

It is not clear from your posts (The ones I read) if you are building for gaming or also for work.

Its intended as an all-around build, through it will be used for daily browsing and gaming. The hardest thing to get right is gaming due to the need for VGA passthrough on a fully virtualized enviroment.

Is this the proper forum to post about my building experience? I would like to receive some comments as the training lab advances. It is a slow long term project.

You may want to create a Worklog Thread, not sure on what part of the Forum they're more appropiate. I suppose that if you create the Thread in the wrong forum, it will get moved to where it belongs.

 

[Headfoot]

Honestly this entire set up is one of those things that would be the holy grail of cool if you can get it working (hypervisor with fully gaming/pci passthrough capable guest OSs) but its just so damn flaky and high maintenance that it's generally just a better idea to run a base Win 7 for gaming and dual boot into your preferred linux distro running your VMs from there. Not as clean or convenient in theory, but it works and its more convenient in practice. Plus it lets you still use K CPUs

 

[RyC]

I agree. While it is possible to get GPU passthrough working, it's usually not worth the hassle. Plus ESXi updates seem to be hit or miss with maintaining passthrough compatibility.

My X10SAT has been running for almost 3 months with no issues though!

 

[fabg]

That one is Buffered

Hello Zir_Blazer,

Thank you. Ordered the memories before reading your last post. It appears ECC buffered memory is OK if using together Xeon E3-xxxxV3, Supermicro X10Sat-O with chipset C226 and socket 1150.

Of course could be wrong, the information in the internet is not in absolute terms. Intel and Supermicro, as well as some vendors, indicate support for ECC, but do not specifically mention buffered or un-buffered. :whiste:

 

[fabg]

TThe hardest thing to get right is gaming due to the need for VGA pass-through on a fully virtualized environment. /Quote]

Probably you already check these links, but according to some internet sites you need the right combination of OS-BIOS-Video card to make it easier. Even then, it appears to be a challenge, good for you.

http://wiki.xen.org/wiki/Xen_VGA_Passthrough

http://wiki.xen.org/wiki/Xen_VGA_Passthrough_Tested_Adapters

Good luck with the project and Happy New 2014!

 

[powerhouse65]

@zir_blazer: I'm sorry to hear that you haven't managed to get VGA passthrough (or passthrough) working. I haven't been on this forum since August, and had to register again under a slightly different name (see my posts under powerhouse64 towards the beginning).

Reading the posts here I can't help but get the feeling that you got lost in all that. So lets try to go back to the basics. For those following this thread and looking for motherboards that have been used to do VGA passthrough, look here: http://www.overclock.net/t/1338063/vt-d-compatible-motherboards. I'm maintaining this list and try to insert only credible information. Many motherboards listed there have a link to a website/forum where a user reports successful PCI or VGA passthrough. Stick to those boards where users have succeeded !!! Check also which BIOS release, if mentioned.

As a rule of thumb, you will have more chances with an ASrock motherboard and perhaps Intel. Some Gigabyte boards are reported to work, BUT some are not! As to Asus, they have fixed some BIOS bugs in some of their AMD boards, and are in the process of fixing VT-d related bugs in some other boards. If and when that happens I will do my best to update the list (see link). The problem with Asus is that they neither specify VT-d in their user documentation nor do they make any kind of commitment. My recommendation: stay clear of Asus unless they change their policy (I made the mistake to buy an Asus Sabertooth X79 and though it works for me now, I won't upgrade the BIOS as it may break things).

The same importance should be paid to the graphics card you want to pass through: As a rule of thumb, stick with AMD !!! If you insist on buying Nvidia, you need a Multi-OS board which starts with the Quadro 2000 and some much more expensive boards. I have and use the Quadro 2000 and it works fine, but these boards are expensive compared to what you get. Here is the list of VGA compatible graphics adapters I maintain: http://www.overclock.net/t/1307834/xen-vga-passthrough-compatible-graphics-adapters. Note: This list is by far not complete, but if you want to be on the save side, pick one of those GPUs.

Instruction on how to get Xen VGA passthrough working with compatible hardware can be found here: http://forums.linuxmint.com/viewtopic.php?f=42&t=112013. This how-to is based on using Linux Mint and I'm the author (or better, co-author as so many people have contributed to it!). There are more tutorials out there and I've mentioned some in a post back in August.

zir_blazer: I suggest you read my tutorial and - if you have no objections against Xen and Linux Mint - try it. Please follow the tutorial exactly step by step. If things don't work, perhaps me or others on that forum (or even here) might be able to help. Right now I have no point of reference on why you didn't succeed, so it's kind of difficult to help.

If you don't mind, please post your entire hardware configuration here, including motherboard and BIOS release, CPU, and graphics card(s).

With Xen, I also recommend using the "xm" toolstack for now (not the default "xl" toolstack). Some instructions are different between the two toolstacks, so check my how-to.

Another advice: go with secondary VGA passthrough. By the way, the VT-d and VGA passthrough tutorials at the Xen.org website, although helpful, can be a little misleading. IIRC they suggest primary passthrough as the method, which is destined to cause frustration.

You have spent so much time in researching, let's get this working. Don't give up!

 

[powerhouse65]

Honestly this entire set up is one of those things that would be the holy grail of cool if you can get it working (hypervisor with fully gaming/pci passthrough capable guest OSs) but its just so damn flaky and high maintenance that it's generally just a better idea to run a base Win 7 for gaming and dual boot into your preferred linux distro running your VMs from there. Not as clean or convenient in theory, but it works and its more convenient in practice. Plus it lets you still use K CPUs

Oh yes, it is the holy grail :thumbsup:. I was in exactly the same situation as the OP about 2 years ago. Now I'm running a Xen hypervisor with Linux Mint 16 and Windows 7 Pro as a VM and I couldn't be more happy! Finally I got Windows where it belongs - a secondary OS in a VM which I only start when I need to. Using LVM formatted drives making a backup of Windows or restoring it is a breeze.

I disagree with Xen being flaky - my system runs rock solid for the past 1 1/2 years. I've started with Linux Mint 13 and Xen 4.1.2, upgraded (or reinstalled the / and /boot) to LM14 and now LM16 with Xen 4.3. All from standard packages delivered in Linux Mint (or Ubuntu, as Linux Mint is based on Ubuntu). Only once did a package update cause trouble - all I had to do was force the Xen packages to an earlier release.

I've documented all this on the Linux Mint forum and received dozens of replies from people who succeeded. The key to success is getting the right hardware. If you stick to proven hardware, setting it up is easier than setting up Windows .

Here a few benchmarks: http://forums.linuxmint.com/viewtopic.php?f=225&t=153482

 

[powerhouse65]

One thing I don't like about X10SAT is that according to the block diagram published in the manual it dedicates half of available chipset PCIe bandwidth to Thunderbolt controller. As a result Supermicro had to hide three PCIe x1 slots, IEEE 1394 and external USB 3.0 controller behind some kind of a switch (PLX8606) with single PCIe x1 uplink....

These are the things that would worry me with regard to PCI passthrough. In fact, I wonder how it would work with these ports? I would definitely check with Supermicro first to see if these "hidden" PCIe slots can be passed through!

 

[zir_blazer]

@zir_blazer: I'm sorry to hear that you haven't managed to get VGA passthrough (or passthrough) working. I haven't been on this forum since August, and had to register again under a slightly different name (see my posts under powerhouse64 towards the beginning).

I managed to get it working two days ago. The problem was that I was ignoring an important error when I used xl create:

WARNING: ignoring device_model directive.
WARNING: Use "device_model_override" instead if you really want a non-default device_model

This is because in most guides, they tell you to use device_model = ‘qemu-dm’ (Yours included, as I checked it among many others). qemu-dm latest release broke VGA Passthorough, so they now instead tell you to use qemu-xen-traditional. The problem was that it NEVER kicked in because as these two warnings says, device_model was getting ignored (Got deprecated on one of the latests Xen versions. Xen documentation for the config file on the wiki is outdated), and when I used device_model_override as instructed, it throwed a different error and didn't even created the VM. This fixed it:

device_model_version = "qemu-xen-traditional"

After that, VGA Passthrough worked flawlessly. I had the VM working for nearly two days with ocassional use with OCCT GPU, Path of Exile, and League of Legends, and no issues (Drivers for the GPU were installed standalone from Add Hardware, no Catalyst Control Panel, heared that it gave issues).
I also even rebooted it a few times without doing a full Dom0 reboot and didn't notice the infamous slowdows on GPUs without FLR (Soft reset). Keep in mind that when I builded Xen 4.3.1-5, I uncommented a line in PKGBUILD file about a Radeon patch, not sure how it would behave without it.

However, there are some quircks with it. When the VM starts (I use sdl = 1 and vnc = 0), I need to have that window active or else it BSODs or doesn't passes the 5770 properly. Path of Exile freezes for a few seconds if I accidentally resize the window size if not running Fullscreen, through I don't know if that is normal behaviator. Otherwise it seems to be rock solid, so you can add Supermicro X10SAT to your VT-d list.
Only thing missing in the VM at the moment is sound. I don't know why there aren't paravirtualized Drivers for it like those that Microsoft Virtual PC had.

Also, I NEVER managed to get Xen to work in UEFI mode, even following the instructions of someone that did it sucessfully here. It always hangs detecting pci devices, and it also seems to not activate ACPI, which Arch Linux in UEFI and Xen in BIOS mode do.

 

[powerhouse65]

One more observation about the discussions here: The OP started out looking for a motherboard that would support VT-d, to allow him (her?) to run Xen and Linux with a Windows VM for games, without having to dual-boot.

The choice of a Supermicro C226 motherboard is quite far fetched, though I understand the reasoning being a server board is more likely to have "guaranteed" VT-d support by the manufacturer, particularly when it comes from a reputable server manufacturer. Yes, Supermicro makes their bread and butter with servers and workstations, where customers often need Linux/Xen/KVM or VMware and PCI passthrough support. But Supermicro is not in the desktop over-clocker etc. business, and probably hasn't got a clue about it. They cannot just rewrite the BIOS to include overclocking (or underclocking) features. It's like asking a truck manufacturer to go and "modify" one of their smaller trucks into a sports car.

Here is what I would consider suitable specs for a basic virtualised gamers rig:

1. Intel / AMD quad-core (or higher) CPU with integrated GPU (IGP) with IOMMU/VT-d/AMD-V support
2. Motherboard/BIOS with VT-d (Intel) or AMD-Vi (AMD) support:
2.1 At least 2 PCIe x16 slots that are arranged to allow double-width GPUs in both slots.
2.2 At least one accessible PCIe x1 slot for add-on USB/SATA/sound card if needed
2.3 At least 2 USB controllers. The chipset will provide several USB-2 and perhaps USB-3 controllers, and often there is an additional USB controller for more USB-3 etc. ports.
3. AMD graphics card (unless you find a Nvidia graphics card thats been tested to work with VGA passthrough, or unless you modify the graphics card to turn it into a Grid or Quadro model that does support VGA passthrough - this is risky).
4. A USB KVM switch, or 2 mice/keyboards, or you can install "synergy" - for gaming you want to pass through the keyboard/mouse so get yourself a KVM switch or two sets of keyboard/mouse.
5. A single display with at least 2 HDMI ports and integrated speakers or a headset connection. The display should allow you to switch between two sources at least. Alternatively, a display with DVI and HDMI port where you can switch between them. Most HDMI graphics cards have onboard sound so having built-in speakers or better a headset connection on the screen can be very helpful.
6. A suitable Windows 7 32/64 bit license. Both Windows 8 and Windows XP are supposed to work too, but sometimes there can be issues.

In any case, get hardware that has been listed as working with VGA passthrough (see my previous posts/links), unless you want to be a hero.

Use the IGP for Linux and the graphics card for Windows(you need to pass through both the graphics card AND the sound chip, for example 02:00.0 and 02:00.1). Also, pass through one USB controller to Windows for the keyboard/mouse. Use a VNC viewer to install Windows, then reboot and install the graphics card driver for your second graphics card in Windows (you discrete graphics card you passed through).

 

[zir_blazer]

The choice of a Supermicro C226 motherboard is quite far fetched, though I understand the reasoning being a server board is more likely to have "guaranteed" VT-d support by the manufacturer, particularly when it comes from a reputable server manufacturer. Yes, Supermicro makes their bread and butter with servers and workstations, where customers often need Linux/Xen/KVM or VMware and PCI passthrough support. But Supermicro is not in the desktop over-clocker etc. business, and probably hasn't got a clue about it. They cannot just rewrite the BIOS to include overclocking (or underclocking) features. It's like asking a truck manufacturer to go and "modify" one of their smaller trucks into a sports car.

Actually, Supermicro DID wanted to get in the enthusiast business. They have a Motherboard, C7Z87-OCE, which shares the same PCB and most features with my X10SAT. Heck, my X10SAT got printed in the PCB C7Z87-OCE. That one does have a full feature BIOS for overclocking with Z87 Chipset. I suppose they could crossbreed both BIOSes if they wanted to, but they don't want to taint their serious Server business with the "overclock it then complain that it crashes". Makes me recall a comment by JF-AMD back in XtremeSystems when everyone requested a Dual Opteron Motherboard for overclocking.

What does exactly the HDMI sound works for? I passed it for my Windows VM, but I don't see how I can get sound out of it. Windows XP has Drivers installed for it, but doesn't appears to be a standard sound device. Also, I don't find the need to passthrough the USB Controllers. Emulated Keyboard and Mouse works fine.

 

[powerhouse65]

I managed to get it working two days ago. The problem was that I was ignoring an important error when I used xl create:

WARNING: ignoring device_model directive.
WARNING: Use "device_model_override" instead if you really want a non-default device_model

This is because in most guides, they tell you to use device_model = ‘qemu-dm’ (Yours included, as I checked it among many others).

That's great news - congratulations and welcome to the club!

My how-to uses the "xm" tool-stack which isn't plagued with FLR or performance degradation issues, as far as I know. I'm running a stock 3.11 kernel and stock Xen 4.3 and didn't have to compile anything, just change some configurations and add a missing link. The "xl" tool stack seems to be different beast, though quite a few including you were able to tame it.

qemu-dm latest release broke VGA Passthorough, so they now instead tell you to use qemu-xen-traditional.

I read about it. Fortunately my Ubuntu 13.10/Linux Mint 16 release doesn't use the latest qemu-dm release . In fact, for anything but bleeding-edge hardware, I prefer to use a standard distribution and not tinker with the kernel and patches.

However, there are some quircks with it. When the VM starts (I use sdl = 1 and vnc = 0), I need to have that window active or else it BSODs or doesn't passes the 5770 properly. Path of Exile freezes for a few seconds if I accidentally resize the window size if not running Fullscreen, through I don't know if that is normal behaviator. Otherwise it seems to be rock solid, so you can add Supermicro X10SAT to your VT-d list.

What do you mean by window / fullscreen? There can't be any window if you pass thru the graphics card - you need to switch the screen to the other graphics card. I haven't used sdl but would go with VNC for installing the Windows VM. Later you only need it occasionally after Windows software updates or crashes that require user interaction while booting. Install a vncviewer and enter xm vncviewer <name-of-guest> as root (or the equivalent in xl slang).

Only thing missing in the VM at the moment is sound. I don't know why there aren't paravirtualized Drivers for it like those that Microsoft Virtual PC had.

Why would Microsoft produce paravirtualized drivers for Xen? It's not that they were to gain from it. We are lucky that we have the GPLPV drivers for disks and networking that have been developed in the open source community.

To be practical, here my suggestions:
1. If your screen has built-in speakers or a headphone port, try to use the sound card on your graphics card with an HDMI link (or display port).
2. Buy a cheap $10-15 USB sound stick - that is what I did. Under Windows, I need sound only as output - I don't need microphone etc. support. So I passed through a USB port, plugged in the USB sound stick and wired its output to the line input on my onboard sound. Now I got sound both from Windows and Linux, at the same time. So I play music on my Linux machine while editing photos on my Windows VM.
3. If sound quality under Windows is important, and you don't need to mix it with your Linux sound, get a nice sound card and pass it to Windows. Then hook up your speakers etc. to it.

Also, I NEVER managed to get Xen to work in UEFI mode...

That's no loss. The best is to stay clear of UEFI, as it means trouble. I'm not even sure if UEFI boot has been implemented in Xen, and if, which release.