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SLI Trouble

mit01

n00b
Joined
Sep 1, 2009
Messages
7
I just bought a second 640mb 8800GTS to use in SLI with my current one (same card), installed the card, turned on SLI, and installed the latest nvidia drivers. However, my performance is much lower than it was with one card. My 3dMark06 scores are 1/3 of what they were and the fps in all of my games has dropped. Also, with my system just sitting at the desktop with no extra programs running, my CPU usage is at 90-95% with my CPU temps at 60C (vs. the normal 40C). I don't know if there may be a common SLI issue that I am running into (either with the physical cards or software issues) or if there is something that I am doing wrong. Any help would be greatly appreciated.

System Specs:
MSI P6N SLI Platinum mobo
E6750 @ 3.0 GHz
2GB DDR2 800 RAM
500GB WD HDD
Corsair tx850w PSU
 
sorry I cant help but why on earth would you buy another 8800gts 640mb for sli at this point? you now have the power usage of the fastest modern card available while getting the performance of a modern lower mid range card. you should have just sold the old 8800gts 640mb and bought a 5770. that little card would have delivered the same or better performance while consuming just over 100 watts as opposed to nearly 300 watts for your 8800gts 640mb sli setup.
 
That's not how it should be; CPU usage should be nominal when at idle. IIRC, the P6N series had a physical connector underneath the 1st PCI-E x16 slot that you flipped over to the "SLI Enabled" side. Have you done this on your board?

In task manager; what process is using all of the CPU?

The best way to test if you have a defective card is to try each one by itself: Run 3DMark with the original card installed, remove it, install the new card, and rerun the benchmark. Are the scores comparable?

- Aux
 
I did flip that connector over.
A svchost process is using all of the CPU. After looking at this a little bit, supposedly this can happen if a piece of hardware is OC'd to an unstable point. I then realized that my original card was an overclocked edition, so I am working on trying to get both cards at the same clock (i cannot put the new card in the first slot because of an aftermarket heat sink). If this doesn't work and if both cards work fine separately, I will post back.

And I got another card to SLI for a couple of reasons. For one, I enjoy creating and modifying computer builds and have yet to work with SLI, so this is more for the experience than for necessity. For two, I was able to pick up a second used card quite cheap. And also, would a 5770 give equal or better performance as 2 8800's in SLI? I thought the the 8800's would be better, but maybe I am wrong.
 
I did flip that connector over.
A svchost process is using all of the CPU. After looking at this a little bit, supposedly this can happen if a piece of hardware is OC'd to an unstable point. I then realized that my original card was an overclocked edition, so I am working on trying to get both cards at the same clock (i cannot put the new card in the first slot because of an aftermarket heat sink). If this doesn't work and if both cards work fine separately, I will post back.

And I got another card to SLI for a couple of reasons. For one, I enjoy creating and modifying computer builds and have yet to work with SLI, so this is more for the experience than for necessity. For two, I was able to pick up a second used card quite cheap. And also, would a 5770 give equal or better performance as 2 8800's in SLI? I thought the the 8800's would be better, but maybe I am wrong.
even if your cards scaled 100%, which they wont, you would not even beat a gtx260. so yeah an 8800gts 640mb sli would not even match a single 5770 in most games. again the 5770 can do everything your 8800gts 640mb sli can do and more while using 1/3 of the power. even if someone gave me an extra 8800gts 640mb I would just sell them both and buy a single card. I guess I just like things simple and dont see the point in using all that power, creating all that heat, and putting up with multi gpu issues when a single $150 card can match or beat it while also having more features.
 
a little bit of an update:
When I try to underclock my original card to no OC'd speeds, GPU-Z and Everest both show only my original card being clocked at those speeds while the new card stays at the overclocked speeds. I was able to get an SLI ribbon so that I could put the new regular card in the first slot and put my overclocked version card in the second slot. However, instead of underclocking to what the card in the first slot is, both cards go to the OC'd speeds. I am not sure if this clock speed is my problem or not, but any input would be great on how to fix it. Also, i noticed that GPU-Z and Everest are both telling me that my original card has 112 shaders while this new card has 96 shaders - not sure if this would cause my CPU usage issue.

Also, I have this CPU issue even when SLI is not enabled as well as when I boot to safe mode
 
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