New RAM, System Highly Unstable

[theexitwound]

The current system:

AMD Opteron 170 Stock
Abit KM8-Ultra (socket 939 latest revision and flash)
Corsair XMS3200 Cas2 4x256MB 2-3-3-6
nV 7800GTX
Windows 7 Beta 64-bit[/list]

The RAM

I bought this ram from eBay and it arrived today. I was running Crucial 2x256 Cas3 low-end ram and 1x Generic 512mb cas3 ram, total of1GB. I felt it was fine to bump that up to a 2GB kit. I went for the Cas2 dual channel setup to push this system as far as It'll go. However, I can't get it to POST consistently and it's flaky if it does.

First of all, When I install 3 of the 4 ramsticks, any 3 in any 3 slots, the system POSTS fine, detects them at SPD (cas3, 3-3-3-8) and it's hit or miss whether Windows will boot. Sometimes it'll return "the header checksum does not match the file cheksum" or some other random errors. Sometimes it'll bluescreen with page_faults. Sometimes, halts on the POST itself.

When the 4th ramstick is installed, the system will refuse to POST 99% of the time. I've changed out the sticks to verify that they all do that, and they do. No matter what 4th slot is open, the system POSTS and may or may not boot into windows, and if the 4th stick is put in, it fails to POST at all.

I've read on Corsair's website that SPD is set to 3 for maximum compatibility across systems, but on AMD systems, this kit should run 2.5-3-3-8 just fine. It's also noted that the RAM is rated at 2.75V, up from the default 2.6V DDR400 standard.

My Attempts

I've changed out the RAM sticks as noted above to verify that all sticks are identical in response. I believe it's a motherboard issue at this point rather than ram.

I DID get the system to post with all four sticks in, only to have it revert to DDR333, 2T Dual Channel 128-bit CAS:2. But it wouldn't get into Windows at all.

With 3 sticks in (1.5GB), the system will post. I attempted to bump the voltage up to 2.7V (The system doesn't do 2.75, either 2.7 or 2.8V is available) but this did not help and seemed to introduce even more crashing.

I threw in my old RAM again and the system is rock stable.

What do I do at this point? Is the KM8-ultra doing something funny? Is it a power issue? The ram was apparently running and working when shipped to me, securely packaged and safe from bumps etc. I haven't had much luck with ram ever, and this is yet another problem that I can't seem to get my hands on.

Where do I go from here? Thanks!

 

[gnomepunk]

I do remember issues with 4 stick of RAM and the nForce 4 chipsets.

Don't worry about your timings until you get your system stable. When you put all 4 sticks in, you will have to run them at 2T instead of 1T. Can you POST/Boot with only 2 sticks in the same color slots (for dual channel)?

 

[imported_harlanpepper]

Yeah, 2x1GB seemed to be the optimal solution for my Asus A8N-SLI 939 board. I think I tried throwing in some random 512MB sticks and it didn't like it.

 

[yh125d]

Lower to 333mHz and relax the timings maybe. 939 does alright with 4 dimms, but 4 x 400mHz dimms is rough on it

 

[RebateMonger]

Originally posted by: theexitwound
I DID get the system to post with all four sticks in, only to have it revert to DDR333!

Dell 400SC boxes (Intel 875 Chipset) would do that. If you put in four sticks of (genuine) DDR400, it'd automatically switch to DDR333 timings.

I'd buy two reliable 1 GB modules, Memtest them to be sure they are stable, and sell everything else that you can. The last Crucial DDR400 modules I purchased last summer were about $12 a Gigabyte after rebate. They may have gone up now, since they likely aren't being made anymore.

 

[theexitwound]

Yeah, pricing on 1GB sticks is now around $25, which is why I snagged the 4x512 for ~$37. The motherboard specifically states that 4 slotted DIMMs should work though, I believe, if I'm reading it right. The system WILL boot fine with 2x512 installed, in dual channel 128-bit 1T timings. It will boot occasionally with 3x512 installed, but often fails to post.

I had 1GB installed, and the reason I bought this pack was to upgrade to 2GBs and get the most I could out of the s939 before changing forward when I could next year. Running Windows7 (or any OS really) with 1GB installed is slowly choking me as times progress. I was hoping this set of ram would perform for me.

So do you all think it's a longshot to have 4 sticks in at all? I understand the performance increase using dual-channel isn't significant, but if it's avaiable, why not use it?

Edit: I can't boot with 3x512 installed either. The system won't stay stable enough to get to BIOS, no matter what the settings are, even at SPD.

 

[Arcanedeath]

The memory controler is in the CPU, I'd suggest uping the vcore some and raising the dimm voltage to at least 2.75 volts if thats what the corsair is rated at your might even want to try 2.8, note 2.5 is stock for pc 3200 ddr not 2.6 (your board might overvolt or default to 2.6 though)

so with just 2 sticks up vcore a bit set the divider so the memory runs at ddr 333 / pc2700 and set the vdimm to 2.75 or 2.8V save and reboot, once its up and you know it works at that setting, try and add the other 2 sticks in and make sure your system is set to 2T cmd rate, running 4 dimms wont be stable w/ 1t.

 

[theexitwound]

Thanks for all the responses!

I managed to get 3 of the sticks installed at spd (3-3-3-8) and the system is stable (so far). It's weird. I had two sticks in at Cas2 and they worked fine. Added the 3rd and no go. Took the 3rd stickout and set the cas to 2.5 and the original two sticks wouldn't boot and stay stable. (?) And then set them to Cas3 and they're fine. Added the 3rd stick and it's fine. I don't understand.

 

[dawza]

My A8N-SLI would automatically ramp down from DDR400-->DDR333 at 2T with all 4 slots populated.

Arcanedeath's suggestions should do the trick- the only thing I can think of is to loosen your timings even further. The performance loss from looser timings is negligible compared to the gain from having sufficient memory (not to mention a stable system).