this is the first time I'm using this platform actively, so please be gentle :-)
My computer consists of the following:
AMD AM2 7750 DualCore
2x2GB noname RAM
CoolerMaster Real Power M700 PSU
Now I bought another XFX9800GTX+, used, but functional when I use it alone.
I put both cards in, provided the first (original) card with the two 6-pin-cables from the PSU (which has two dedicated slots for that), and bought two split-cables, that on one side have 6-pin connections and on the other have connections so I can plug them to the S-ATA power cables.
So both cards are provided with electricity, one through dedicated cables, the other through split-cables.
I connected the 2-way-SLI-bridge to the very left of both cards.
Now, what happens when I start the computer is mostly that power goes on, you hear the two card's fans charging up, then down, and nothing further happens. Every 15 secs or so the GPU fans spin up, down, and nothing more.
Sometimes then I can't even start my computer (same behaviour) when having taken out the 2nd GPU, which is when I use a jumper to reset the motherboard's BIOS.
Mostly then I can boot normally into Windows.
Sometimes, right after resetting the BIOS, when I put in the 2nd GPU card, the computer will boot up and loads into Windows, but the Nvidia software does not show any SLI options. Checking the device manager, there is only one card listed.
That happened only twice though, and the first time I thought that maybe my Nvidia software was outdated, so I downloaded the newest one, but the installation got stuck. Upon reboot, the same old problem came up - computer won't boot much.
I do think that both GPU's have the same BIOS version, having looked at that in GPU-Z.
Does anybody have any idea what I could do, what I've missed, or misunderstood, or fouled up? :-)
The unit would have to be defective to not be able to supply enough power to the system so I doubt that it is the problem but keep it in mind. Try to test each card alone in that system even though they are known to be good but is to search out for issues. I am thinking that it is either the cabling or the board at this time.
I am doubtful that the bios is of any issue. I believe that it is your board or there is a power issue. If both cards work alone then it can't be a bios related issue on any of the cards nor the board. A bios issue would leave the cards not working at all on that bard but working on other boards with no issues.
The result it gives me is that I should have a 500W-PSU for single-GPU-mode, and a 600W-PSU for SLI-mode. I own a 700W-PSU explicitly stating that it can do SLI.
Thus I tend to hope that my PSU is not the culprit.
I tried using different BIOS files from MVKTech, the problem I now have is that in some positions of the SLI bridge the games show flickering, and in some not, and when I remove the bridge, there's no flickering at all.
In all cases though the games tend to crash. I just got my first message from Windows saying that the driver crashed and then recovered...
I just opened a support ticket with Cooler Master, asking 1) if my PSU is sufficient for my setup, and 2) how to connect both video cards to the PSU exactly.
What I forgot to mention last night is that since I updated the GPU BIOS of both cards to 'XFX 98GTX+ Rev.02'
from MVKtech, the computer won't start up anymore when Windows wants to use its generic drivers, but starts normally with the newest Nforce driver set.
Also, so far, in World In Conflict I am yet to see an fps-change, so I guess when selecting SLI-mode, it doesn't really do so.
I have alot of other stuff in but for that config I'd be thinking more along the lines of a good quality 1kw psu min.
2kw? That would have to be a dual phase unit as most wall outlets are only rated for 1.5kw. As for the psu that you linked in another post that brand is not commonly known and questionable as far as quality is concerned. You do not need 1k for just two meager 9800gtx in two way sli. 700w~ from a high quality unit is more than enough.
alright... so I guess there's not that much of a difference between 850W and 1000W, price-wise.
Also, I bought my PSU in late 2008, and it has lived through many many system changes and sometimes looked like the probable culprit when the system wouldn't start up and I had to cold-restart in order for the computer to work...