Holy SLI 7800GTX = System Memory Hog

[papaHesch]

Can anyone explain this to me? Just got a second 7800GTX to use for SLI in my a8n-sli premium board and these babies really eat up the system memory. I have 3 gigs of memory in the board but each 7800GTX is limiting my total system memory by 300 Megs. Thus, with both of these cards in my rig I have 2.4 gigs of available memory. My Bios makes me aware of total and available memory to the OS but I did not notice until I looked at the system properties in XP. This seems a little excessive; do these cards really use that much system memory or am I missing some BIOS configuration (i.e. aperture size etc) that is allowing this to happen? Is anyone else with a 7800GTX setup seeing the same thing? Should I even be concerned?

Thanks,
PapaHesch

 

[Ackmed]

Each 7800GTX doesnt take up 300megs. Adding a second GTX to my system didnt take up any more memory.

What has likely happened, is that you added more ram, the same time as the card? x32 XP cannnot see 3gigs of ram. You'll need x64 for that. Also, you are not running dual channel with 3gigs, making matters worse. I would go back to 2gigs, see how it looks then.

 

[Powermoloch]

lolololololol

 

[Hacp]

Ya adding Nvidia cards can do that. 2x 512 GTX is worse. It will also kill the 2nd core in an X2 and disable sound permanently. FUrthermore, Hard drives are regulated to only 4200RPM and the DVD part of a DVD drive does not work. I don't know why Nvidia hasn't fixed these problems yet.

 

[dguy6789]

Originally posted by: Ackmed
Each 7800GTX doesnt take up 300megs. Adding a second GTX to my system didnt take up any more memory.

What has likely happened, is that you added more ram, the same time as the card? x32 XP cannnot see 3gigs of ram. You'll need x64 for that. Also, you are not running dual channel with 3gigs, making matters worse. I would go back to 2gigs, see how it looks then.

You have a bit of misinformative information.

Windows XP can handle 4GB of memory on a system. But, a single application can only use up to 2GB on XP.

You could run dual channel with 3GB if you have 2 1GB sticks and 2 512 sticks and have a 1Gig and 512MB stick in each channel.

Windows X64 can use something like 128GB of memory or something like that.

 

[Fadey]

How can i tell if my memory is running dual channel? i got 4x512 (yes i know its bad buts its how i upgraded). I got an asus A8N-E board and i looked around the bios and i couldnt find it any where.

 

[otispunkmeyer]

Originally posted by: Fadey
How can i tell if my memory is running dual channel? i got 4x512 (yes i know its bad buts its how i upgraded). I got an asus A8N-E board and i looked around the bios and i couldnt find it any where.

you have all the slot filled = dual channel

you get single channel when you have just one stick, or one stick in each coloured dimm (ie i pressume you dimm slots are two diff colours ie 2 are purple, 2 are green 1 in green 1 in purple = single channel i think)

and windows can see up to 4Gb.....its just a program can only use up to 2Gb

 

[Zstream]

Reason why this happened is because you have your aperture size set to high. Change it to 128mb or 64mb in the system bios

 

[Squally Leonharty]

Originally posted by: Zstream
Reason why this happened is because you have your aperture size set to high. Change it to 128mb or 64mb in the system bios

PCI-E motherboards no longer work with Aperture Size. I also have an Asus A8N-SLI Premium and I don't recall such an option in BIOS.

Anyway, I'm not sure why that happened to you, but if you know someone with an SLI motherboard, try out your two cards there and see if the same thing happens. If it does, I guess it's normal then when using large amounts of memory; otherwise it's your PC. Try reinstalling XP?

 

[Topweasel]

Originally posted by: otispunkmeyer

Originally posted by: Fadey
How can i tell if my memory is running dual channel? i got 4x512 (yes i know its bad buts its how i upgraded). I got an asus A8N-E board and i looked around the bios and i couldnt find it any where.

you have all the slot filled = dual channel

you get single channel when you have just one stick, or one stick in each coloured dimm (ie i pressume you dimm slots are two diff colours ie 2 are purple, 2 are green 1 in green 1 in purple = single channel i think)

and windows can see up to 4Gb.....its just a program can only use up to 2Gb

Actually Windows Will only show a max of 3 GB by default even though it can adress more then that. If forgot the reason for it, I remember something about conflicts with Photoshop and other memory hog programs having an issue with the last Gig.

 

[Cheesetogo]

Originally posted by: Topweasel

Originally posted by: otispunkmeyer

Originally posted by: Fadey
How can i tell if my memory is running dual channel? i got 4x512 (yes i know its bad buts its how i upgraded). I got an asus A8N-E board and i looked around the bios and i couldnt find it any where.

you have all the slot filled = dual channel

you get single channel when you have just one stick, or one stick in each coloured dimm (ie i pressume you dimm slots are two diff colours ie 2 are purple, 2 are green 1 in green 1 in purple = single channel i think)

and windows can see up to 4Gb.....its just a program can only use up to 2Gb

Actually Windows Will only show a max of 3 GB by default even though it can adress more then that. If forgot the reason for it, I remember something about conflicts with Photoshop and other memory hog programs having an issue with the last Gig.

I belive that's because the 4gb that windows is able to address includes the page file. I think that you have to disable to the page file to get the other gig.

 

[LTC8K6]

CPU-Z will tell you if your mem is running DC.

 

[StumbleBum1]

Originally posted by: Hacp
Ya adding Nvidia cards can do that. 2x 512 GTX is worse. It will also kill the 2nd core in an X2 and disable sound permanently. FUrthermore, Hard drives are regulated to only 4200RPM and the DVD part of a DVD drive does not work. I don't know why Nvidia hasn't fixed these problems yet.

:laugh::roll:

 

[SKoprowski]

I recently updated to a vencie core Athlon 64 in my system below. I got all excited cause I could now run all 4 memory slots at 400. I had two 1 gig sticks of pc3200 memory already installed and I decided to install two more 512 pc3200 sticks. Well......the computer booted with no problems but reported 2.2 or 2.4 (I can't remember now) usable memory with a total of 3g. Windows recognized it as 2.2/2.4. I was told it was because the memory is reserved for the 2 video cards and the pci Audigy 4 and it is a common thing. I did a google search and found out the info. I just took out the memory and stayed with 2g for now.

 

[papaHesch]

Thanks for all the info. I am currently running xp32 and xp64 on the same machine and both post 2.4 gigs of memory. The Bios is telling me before the OS boots that there are only 2.4 gigs available. I assume that it is some memory mapping BS with the video cards but this is out of control! Skoprowksi, do you remember where you found this information. I want to try and figure out if upgrading to 4 gigs will at least get me to 3.4 gigs. I do a lot of video and photo editing with this compute besides games and the extra memory actually does make a difference.

Thanks,
PapaHesch

 

[Nextman916]

Papahesch im looking at your rig and you have a a killer system, but why do you keep onboard sound? Dont care about audio quality or what?

 

[kamranziadar]

Make sure you have matching all the memories. If you have different brand that could be the problem, 7800GTX should not take any system memory at all.

Try go back to 1GB and see what happens.

 

[papaHesch]

Nextman,

Usually use headphones for audio and have been reasonably satisfied with average HD/EAX audio on the board. I want to hear the new x2 board from creative but have not seen a demo computer with it on. Christmas is around the corner and if the sound is considerably better I might go for it. I am usually more concerned with raw speed, silence, and graphics and thus sound is the last thing I spend money on. Thanks for the complement.

Kamranziadar,

All the memory is the same brand and model but of different sizes. I have two 1 gig sticks and two 512 meg sticks running in dual channel. I will try running the two 1 gig sticks and see if the available memory goes down by 600 megs. If it does not then I think the cards have some weird memory addressing issues above 2 gigs and I have no clue how to fix this. Any help with that discussion would be greatly appreciated.

papahesch

 

[Ackmed]

Originally posted by: dguy6789

Originally posted by: Ackmed
Each 7800GTX doesnt take up 300megs. Adding a second GTX to my system didnt take up any more memory.

What has likely happened, is that you added more ram, the same time as the card? x32 XP cannnot see 3gigs of ram. You'll need x64 for that. Also, you are not running dual channel with 3gigs, making matters worse. I would go back to 2gigs, see how it looks then.

You have a bit of misinformative information.

Windows XP can handle 4GB of memory on a system. But, a single application can only use up to 2GB on XP.

You could run dual channel with 3GB if you have 2 1GB sticks and 2 512 sticks and have a 1Gig and 512MB stick in each channel.

Windows X64 can use something like 128GB of memory or something like that.

No I dont. I didnt say it couldnt use more than 3gigs of ram. I said that it couldnt see 3gigs of ram. Which is whats happening here.

And I assumed he was running 3x1gig of ram. It was wrong of me to assume, but it seems like what he is doing. And if thats the case, he is not running dual channel.

I still suggests he takes out the 3rd gig, and try just 2gigs. His system will see 2gigs, because the GTX's dont take up memory.

 

[Peter]

The reason is that each 512-MByte card consumes at least 512 MBytes of system address space. This is NOT memory consumption.

The reduction in available RAM comes from the fact that everything you have must fit into 4 GBytes, which is the total address size of any 32-bit machine (or a 64-bit machine running a 32-bit OS).

Thus, twin 512-MB graphics cards, the rest of your I/O, plus all the essential misc system stuff easily amount to 1.5 GBytes of consumed address space - and only the remaining 2.something GBytes of space are available to map RAM into, completely regardless of how much RAM you actually have.

64-bit- or at least 36-bit-enabled machines can remap the remainder of the RAM to above-4GB.

 

[phantom404]

Strange...I have 2gig of Ram and windows shows 2 gigs of ram. Never seen your problem before and I'm running 2 GTX KOs.

 

[Topweasel]

Someone said that it was the same for WinXP 64bit ED. Is their a way to change this for that. Just currious as I planned on getting a second GTX a little later, and I absolutely plan on getting a nother 2x 1GB chips. I am running WinXP64 as we speak (well home computer as we speak I am at work using a 1.5GHz P4 with win2k).

 

[papaHesch]

Ackmed,

I am using two 1 gig sticks and two 512 MB sticks running in dual channel. All of the same brand and model besides the size, Patriot LL PC 3200.

ch1:512MB
ch2:1GB
ch3:512MB
ch4:1GB

If ch1+ch2=ch3+ch4 are the same then dual channel works great.


Peter,

I believe what you are saying is happening but the numbers do not add up for me. Information:
3 gigs of total system memory
2.4 available
over 4G remapping enabled in BIOS
XP32 and XP 64 both post the same available memory (2.25 gigs)
Bios says 3.15 gigs total system 2.4 available memory
I have two 256 MB 7800 GTX video cards.
Before I put in the second video card my system posted 2.8 gigs of available memory (2.75 in XP)

I still have a couple questions and if there is a way to fix this. I assume this will become a common problem as more people break the 2 GB barrier (I am going to take the two 1 Gig sticks out midday and see if the total system drops the same amount). I still do not understand why the video cards would not address their memory above 3 gigs and not use the available system memory. Is their a way to force the video cards to do this? How do you force XP64 and the Bios to remap the memory above 4 GB range? I have enabled the 4G remapping function in the BIOS with no change.

Thanks,
Papahesch

 

[Ackmed]

It is NOT the video cards failing to address their memory. Its the OS not addressing 3gigs of system memory. You dont force x64 or the bios to remap anything, to see and use more than 4gigs. Its dont auto.

Either upgrade to x64, or take out some memory if it bothers you.

 

[papaHesch]

Ackmed,

I would agree with you normally but I am running both XP32 and XP64 with the same result of 2.25GB posted. Plus the Bios is telling me that I have 3.12 GB of memory available but only 2.4GB is usuable to the OS at Post or in the Bios. Basically, every time I add a 7800GTX to my rig the it eats up about 300MB. When I have one card installed it will post at ~2.8GB. Unfortuantly there is a more complicated answer out there to this problem.

Papahesch