Vista Ultimate + SLI + 8Gb memory

Hi, I've been poking at this for about 8 months, touring the net and finally given up hope of stumbling across the answer. So here goes! any help would be extremely gratefully received as I'm completely out of ideas.

I have the following set up:

Vista 64 Ultimate SP2
Gigabyte GA-M750SLI-DS4 Nforce 750a (Socket AM2/AM2+) PCI-Express DDR2 Motherboard with latest BIOS
AMD Phenom II X4 Quad Core 920 2.80GHz (Socket AM2+)
OCZ ModXStream Pro 600w Silent SLI Certified Modular Power Supply
Kingston HyperX 8GB (4x2GB) DDR2 6400C4 800MHz Dual Channel (KHX6400D2LLK2/4G)
2xZotac GeForce GTS 250 512MB GDDR3 PCI-Express Graphics Card

In XP 64 it all worked fine. However I wanted SLI to work with dual monitors so upgraded to Vista as I was told it was only supported in that OS (obviously this was pre 7)

Now, if I boot with the SLI and all the memory installed it black screens just after the windows splash screen (just before the login details pop up).

If I boot with 1 graphics card and all the ram in, everything works fine and all the memory is seen

If I boot with both graphics cards in SLI and 2 Gb ram installed, everything works fine.

If I try to add the memory after SLI/OS has sorted itself out, we're back to black screens.

Thanks in advance

did you try a driver fix of some sort?

I've tried installing 2 different generations of chipset drivers and 2 or 3 different generations of graphics drivers. It was trying the latest of both that finally prompted me to give up and seek help.

did you try a bio's update for your motherboard?

Sorry, should have made it stand out a little more in the spec (is tagged on the end of the motherboard spec), have flashed to the latest version of the bios (via a middle version)

hmmmmm......... have you got a extra hard drive you could try a reinstall of vista?
and see if its something with the one you have installed now?

Sable said:

Now, if I boot with the SLI and all the memory installed it black screens just after the windows splash screen (just before the login details pop up).

Click to expand...

so, you boot and see the splash screen and black screen for good or black screen until the login screen comes?

do you have the monitors hooked up to the primary card and is the bios set to have the primary display as PEG1? from my experience (with radeons in crossfire) if i have my monitors hooked to the secondary gpu, i see the boot screen, then black screen until the login screen.

(i've always had my bios set to PEG1, so i don't know how it would boot if the monitors were hooked to the secondary gpu with the bios set to PEG2.)

Sorry, I'm wrong in my original wording there (I wrote the post twice as the first got eaten by the internet and was a little scrambled the second time through), the machine boots till point where the vista logo should pop up (just after the progress bar), but instead black screens and never recovers . Sometimes, it might reboot itself during the black screen, but thats rare.

Both monitors are plugged into the primary card (the hardware setup is identical to when it was an XP64 machine). I've long suspected/hoped its a bios settings issue as I'm pretty clueless when it comes to bios'. I can follow instructions to flash them etc. but I wouldn't know how to configure them properly to a configuration without instructions from somewhere. I'll have a look for the primary display setting when I get home from work, but would have thought something like that would be a problem if set wrong with one card installed as well as 2 in SLI, which the machine is currently running with?

Is it possible for memory voltage settings to cause the problem? I saw something about it on a forum once, but don't know enough about it to evaluate and it doesn't strike me as something to just try out through random fiddling.

thepizzaman said:

hmmmmm......... have you got a extra hard drive you could try a reinstall of vista?
and see if its something with the one you have installed now?

Click to expand...

I built 2 identical machines on the same hardware config (one for me and one for the mrs), though she has different programs installed, and I've not managed to get SLI functioning on either with Vista.

Does anyone know if there are bios settings that vista 64 would be sensitive to that xp 64 wouldn't?

Sable said:

thepizzaman said:

hmmmmm......... have you got a extra hard drive you could try a reinstall of vista?
and see if its something with the one you have installed now?

Click to expand...

I built 2 identical machines on the same hardware config (one for me and one for the mrs), though she has different programs installed, and I've not managed to get SLI functioning on either with Vista.

Does anyone know if there are bios settings that vista 64 would be sensitive to that xp 64 wouldn't?

Click to expand...

hm....... i'm not sure..... time to get a bio's expert in here...

Sable said:

Does anyone know if there are bios settings that vista 64 would be sensitive to that xp 64 wouldn't?

Click to expand...

to the best of my knowledge, the only bios setting that should be enabled for vista that is not required for xp is the HPET (high precision event timer). i know it would kinda be time consuming, but i'd try to disable sli, then remove one videocard and test it by itself. then remove that one and install the other and test it by itself. i saw that you updated your bios, but did not see if you had installed motherboard and chipset drivers for you particular board that are vista 64 bit. if you haven't, that would be my next suggestion.

Drivers are the latest, and have tried a 2 or 3 different generations of drivers for both graphics and chipset over the months (using driver sweeper each time). It was trying the latest ones and them failing to fix it that prompted me to bite the bullet and seek help - usually enough web research can get me round most problems, but google couldn't save me this time.

I'll have a look at the HPET setting when I get home. Thanks!

ps. I've been running the PC for 8 months on just one card and have switched them about a few times whilst trying to get the machine to work in SLI. This was how I found that removing all but 2gb would allow the machine to boot up with both cards in and SLI enabled but failed again when more memory was added.

just some other thoughts...

is your sli bridge connector securely connected? are the cards themselves fully seated in their respective slots? are the pcie power connectors from your psu properly seated and connected?

these may be things you've already checked / done, i was just thinking of possibilities...

yeah, as I say, if I take all be 2gb out then sli works fine and vista boots normally. its the sli memory combo that seems to cause the problem

you've run memtest86+ on your ram?

I've not, but with only one card in I can run happily with all 8gb in and windows seems happy with it all. Should I run the test anyway?

yes it might be worth it

So I take it SLI + 4GB does not work either?

Have you tried removing the SLI bridge, leaving both cards installed + 8GB and seeing if it boots correctly?

yep, 4gb fails (not tried 3 as I only have 2gb sticks, but assume that would be fine).

Tried taking the bridge out, but only tried it once and it crashed quite badly. But I didn't try any fiddling with that to see if I could get around it.