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8800GT's in SLI frames drop and 3dMark06

B

badnewcastle

Golden Member
I have 2 EVGA 8800GT's, one is SC and one is KO. Clock speeds are (core/mem) 650/1900 for the SC and 675/1975 for the KO.

The problem I'm having is that when I enable SLI the core clock speed of GPU 0 (KO card) drops to 399/810. The SC runs at 650/1820 <-this is fixed

All my games play somewhat normal despite the slower speeds in SLI. When I say normal I mean SLI is 2-5 FPS lower then if I disable SLI. So really that's not normal and makes SLI completely pointless.

I'm using Rivatuner to control fan speeds and underclock the shader clock. Now in Riva tuner and I can't do anything with the overclocking features now.


edited title
 
That sounds wierd, but I assume that's why everybody always recomends using 2 of the "exact" same cards for SLI ....
Maybe newwer drivers from Nvidia would help? Otherwise no idea here ...
 
The clockspeed seems odd,

What games and what resolution are you playing at? Playing at like 1280x1024 you will hardly see improvement. And not all games scale well with SLi
 
I haven't played too many games, really just ran benchmarks... Crysis and Grid are the 2 games that I played where it would be noticeable, COD4 gets minimum of 75 FPS with everything on.

Resolution is 1680x1050.

3dMark06 results are as follows (rounded to the nearest 100) and I attribute the higher scores to having two sets of memory as by bumping my cpu up a little more and oc'ing my KO in the past has netted bigger gains (closer to 14000).

1280x1024 - 11500
1280x1024sli - 11800

1680x1050 - 10200
1680x1050sli - 12800



 
Rivatuner & Nvidia Tools. Also, don't know if matters but my PSU is Thermaltake 750w, I'm on able to oc in either program as the feature is grayed out.

Rivatuner shows 4 monitors when not in SLI with core clocks like this according to the monitor

vga adapter: viewsonic xxxx 399mhz
vga adapter: <default> 650mhz
vga adapter: <default> 650mhz
vga adapter: <default> 650mhz
 
Well I got at least part of it fixed.... GPU-Z and the others now read the right speeds.

But... maybe this should be another top? I will edit title...

Problem now is that when I run an individual card (physically there is only 1 card in the system), in the top slot every thing is hunky dory but when I drop it down to the other x16 slot, my 3dMark06 score drops from 11400 to 8800.

I know Crysis isn't the best game to test SLI but putting SLI shouldn't drop the rates, right? It does on my system right now.
 
One thing make sure your BIOS on each card is updated

Can you check the link width that it shows when either card is in either slot?

Like test this

Card A Slot A
Card A Slot B
Card B Slot A
Card B Slot B

Find out what link widths you get for each choice, and 3dmark score too I guess.
 
Originally posted by: BassBomb
One thing make sure your BIOS on each card is updated

Can you check the link width that it shows when either card is in either slot?

Like test this

Card A Slot A
Card A Slot B
Card B Slot A
Card B Slot B

Find out what link widths you get for each choice, and 3dmark score too I guess.
Click to expand...

When I do this test, both cards perform equally well ~11,450 in 3dmark06 in Slot A, and both perform equally bad in slot B ~8850.
 
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