Question about vdimm on AI7

homer77 · Jul 25, 2005

I recently purchased a Abit AI7 to replace my fried Asus P4C800E-dlx.

I picked this board because it has the 3.2v vdimm option. However, when I boot into windows, it only reads 2.85v on mbm5. I am pretty sure it's not 3.2v because I kept getting BSOD with memory dump message. My UTT rams are capable of 225fsb at 3.2v under memtest86, which doesn't boot into windows.

I find this problem to be very weird, I don't see why or how Windows can/would limit the vdimm. :shrug:

Am I doing something wrong here? Can someone give me some pointers? I would really like to run 3.2vdimm on the mb.

batboy · Jul 26, 2005

What does Abit EQ say for vdimm when you have it set for 3.2v? My AI7 undervolts vdimm a little, but something like 3.18v when set to 3.2v. Another thing to check is make sure the last two game accelerator settings are disabled (this will be in the same menu as the RAM timings (advanced chipset menu I think).

homer77 · Jul 26, 2005

batboy said:
What does Abit EQ say for vdimm when you have it set for 3.2v? My AI7 undervolts vdimm a little, but something like 3.18v when set to 3.2v. Another thing to check is make sure the last two game accelerator settings are disabled (this will be in the same menu as the RAM timings (advanced chipset menu I think).

Thanks for the tip on the accelerator, I didn't know that.

As for the Abit EQ, when I set the vdimm to 3.1v, the EQ reading varies anywhere from 2.9 to 3.08v which is too big of a fluctuation for my liking. I'll try to disable the accelerators tonite and see what happens.

batboy · Jul 26, 2005

The game accelerator settings won't have anything to do with the voltage problem, but sometimes does cause instability with the memory. Don't know what to say about the vdimm being so low and flucuating so much. That don't sound right. The power supply you have should be plenty good enough. What do your 3.3v and +12v rails look like under load?

homer77 · Jul 26, 2005

3.3v and 12v reads 3.35 and 11.90 under full load, as i suspet my psu is not the problem.

however, i just tried disable the last two settings, CDC and something read relay and set the vdimm to 3.1v again. this time, when booted into windows, the vdimm didn't drop lower than 3.03v. i need to do more testing to see whether the game accererator did have any effect on vdimm volts.

batboy · Jul 26, 2005

That seems a little better. Maybe you are back on track now.

I know you want the RAM timings to be as tight as possible, but on all my Abit mobos (AI7 and IC7) if I relaxed the RAS to CAS delay one notch, that always gave me higher overclocks.

homer77 · Jul 26, 2005

so instead of 2.5-3-3 do 2.5-4-4?

hawtrawkr · Jul 26, 2005

id still try the 2.5-3-3 your vdimm should slightly undervolt like batboy mentioned but it sounds like its still running low for having it set @ 3.2v

homer77 · Jul 26, 2005

for the UTT, it still errored out 2.9v @ 220fsb. that's why i want to push them harder so i can use them with my tccd for 2gb total.

i'll try more test later tonite.

batboy · Jul 26, 2005

He's at 3.1v I think, so it's undervolting about 0.1v. I would try to stay at 2.5-3-3-6 if possible, maybe bump up to 3.2v but you might try 2.5-4-3-6 just to see if that helps any if you are trying to keep the vdimm down. I'm assuming you are still using the 1:1 ratio, right?

homer77 · Jul 26, 2005

ya, still running 1:1. i just need the rams to reach 230 for now and i m happy.

otherwise i'll just trade them for a pair of tccd then i don't have to worry about running at 3.2v.

{PMS}fishy · Jul 26, 2005

Mine sat at around 3.15v.

The MB can also be modded to ~0.1v less than the 3.3v.

If you have a week 3.3v you will have a week, unstable, low vDIMM.

hawtrawkr · Jul 26, 2005

{PMS}fishy said:
If you have a week 3.3v you will have a week, unstable, low vDIMM.

thats a great point. out of curiosity have you been checking the psus rails with a dmm or through mbm?

homer77 · Jul 26, 2005

last time i checked it was about 3.28v under load. i don't think it dropped much at all, but i'll check again tonite.

Question about vdimm on AI7

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