I recently built a computer- cpu, i5 750, mobo, P55A-UD5, 4gb of g.skill eco, a second 9800GT to compliment my first one and a new seasonic x-series 750W, running windows 7 untimate 64bit. I have built quite a few computers but with this one all the right drivers are installed but every time i shut down my computer for the night and get back on it in the morning instant BSOD every time i start it up. Then when i restart it it BSOD again, and again and again untill i go into bios and load fai safe defaults even though it is on the default settings or if i remove one of the graphics cards when setting failsafe defaults doesnt work. then eventually it will start again with out BSOD till the next morning. Now i have a slight feeling it could be the graphics. I have tested my HDD's and my ram. The thing with the graphics cards is that i've had the first one an MSI one for a few years it uses a 6pin mobo connector and has slightly higher clocks compared to my xfx one but the xfx one doesnt have a power connector (i think its a newer design) it also has lower clocks. I dont know if it is the gaphics cards or the drivers that are having issues it seems that if i remove one of the cards (the xfx one) windows will boot fine then i can whack it back in and do some gaming. Another thing might be the ram it is that new eco stuff from g.skill that uses 1.35v but my mobo doesnt like that so it puts it to 1.5v, but i'm am not sure. If you need any of the report files from windows just say. the graphics drivers i'm using for sli were the 196.21 nforce windows 7 64 bit drivers.
Do you overclock? Also RAM timings (and voltages in your case) can cause that sort of instabilities. Since your motherboard changes the VDram to 1.5V it means that it has trouble operating it at its default 1.35V for some reason. So every time you reset the BIOS to failsafe it defaults the VDram to 1.35V and therefor can't boot properly.
I suggest you flash to your motherboard's latest BIOS and stick with a stable voltage for your RAM even if it is a bit higher than stock.
If your computer will boot with a single card just fine then the problem when adding two cards is either an issue with running both cards together or a Power issue. I doubt it's a power problem.
I don't know why you'd think it was RAM if you can boot successfully with a single card.
Just to be clear:
1) Boot with Video Card #1 only,
2) Boot with Video Card #2 only,
3) Boot with Video Card #1 in the top slot and #2 in the bottom
4) Switch around the cards
5) Make sure any SLI and Graphics BIOS settings are properly set
6) Make sure your SLI connector is seated properly
7) Look for Motherboard Power connections which can stabilize the graphics card power
You should be able to boot two nearly identical cards in SLI. NVidia did a lot of work so that you could use slightly different specs and manufacturers.
The SLI drivers should drop the speeds of the faster card to match the speeds of the slower card so I'd probably put the slower card in the PRIMARY slot.
- check for a motherboard BIOS update
- run Memtest overnight (again, I don't know why RAM would be an issue if it works with a single card though I'm concerned if your 1.35V RAM is running at 1.5V.)
- Can you manually adjust your RAM voltage?
*It REALLY shouldn't matter but you could try running Memtest with a single card installed and Memtest with two cards installed. I'm a computer tech with a lot of experience and I've seen weird problems that don't seem like they should be related so do this with Memtest just to verify your RAM works with two cards.
Hey guys thanks heaps for your help. The reason i though i could be the ram is because other people were having some issues with this ram because of the really low voltages and the mobo auto changes the rams voltage to 1.5v even with fail safe defaults. I can change it and i do. i have tryed the XMP profile but it becomes unstable. I think it is a mixture of the cards and the ram. i will be changing the graphics cards slots arround in a few minutes. I do have another bios to use but it is a beta bios and it does say that it adds support for new ram (possibly mine). and no i havnt overclocked but i will be doing so when I choose a cooler.
I will also run memtest overnight and the timings are currently at stock cl9.
First time running sli so thanks for the pointers and i realised that they should work together i've been reading the green teams site.
I've seen a lot of people with this issue and many who haven't resolved it. Gigabyte did release a new BIOS this past week so it might help to get that. One of the descriptions in their change log is increased memory support.
If you "Load Optimized Defaults", what does it set the RAM's V to? Have you tried manually changing it to 1.35 V and testing for stability?
In the Memory section in BIOS, try setting "Performance Enhance" to Standard.
Yeah thanks for the help again. I've changed the graphics slots arround the slower card is now the dominant one and i updated the bios and i am currently running the ram in its XMP profile at its correct settings all seems to be running smooth. I will have to wait till tomorrow morning though to know for sure as thats when the BSOD often happens.
Well hit the power button this morning and bam BSOD. Tryed two more times same result. Reset the Bios to default settings and it booted. I've tryed all of your suggestions to do with the graphics cards and i updated my bios to F6d it might me the ram if you want i can give you guys the report files from windows but at the moment it could be the ram as i have heard many great things and many bad things about this ram D:.