View Full Version : SLI Picky on which Slots being used?

02-20-08, 08:59 PM
I have:
EVGA 8800 GT that clocks at 650/950
BFG 8800 GT that clocks at 625/900
(The EVGA was a fluke that I got it. Then the only thing I could find a week later was the BFG)

I downloaded the new 174.12 drivers. I had to format so I waited to install those until after that. Prior to formatting I cleaned my comp and put the two video cards back in. In reverse order compared to before.

Installed the drivers, load up Crysis. The loading screen, parts of the image would flash back and forth from normal to blue. During the benchmark, parts of the sky would flash a darker blue, and parts of the landscape would flash back and forth like it was artifacting. Wasn't a blue bar across the screen hiding everything behind it, but blue attached to physical objects like trees, and land scape. The texture itself had a transparent blue overtop of it. But only about 20% of the world had this. Rest of it was fine.

I uninstalled the drivers, revert back to the original ones I was using. Same problem. So I took out my video cards, reversed them, booted up. Problem went away.

I thought maybe it was because of the clock speeds. But I bench marked both cards at 650/950 without a problem. And even ran most of a benchmark at 700/1000 with both cards before it crashed. No blue artifacting though.

Also to note. It only had that blue artifacting during SLI, when SLI was disabled everything was fine. I checked to make sure the cards were secure and seated properly.

To sum it up:
EVGA card in PCI-E Slot 1 and BFG in Slot 2 = blue artifacting
BFG card in PCI-E Slot 1 and EVGA in slot 2 = fine

Any Idea as to why?

02-20-08, 09:53 PM
If slot 1 is the primary and this is when the artifacting occurs I would guess that it's due to the BFG card having it's memory overclocked to the EVGA cards memory speed and not liking running an application like Crysis that really sucks up the memory (way more than 3dMark06).

02-20-08, 10:24 PM
Run the ATITOOL test on both of them ,one at a time in the machine and see how far each will over clock without artifacting .Then you could flash the cards at the same speed and that should take care of the problems ,if you do not like flashing you Bios then run it the way that it runs without artifacting.

02-20-08, 11:01 PM
Set the clocks on both cards to 625/900.

02-21-08, 01:12 AM
Yes, SLI is picky on which slots being used. For 2-way SLI, use slot 1 and slot 3, the blue slots on the P5N32-E Sli Plus. Slot 2 (white) only runs at 8x speed.

02-21-08, 06:33 AM
1) It's not the clock speeds. I have ran both fine, with testing, at 650/950 without any artifiacting or problems at all with the bfg first and evga second. So it's not that.
And just to be absolutely sure. I ran both cards at 600/900 and the problem still persisted when the evga was first and bfg was second.

2) Both slots are 16x. I have the hybrid 650i/570i and I am using both blue slots. I totally forgot about the middle pci-e slot when I mentioned it above. I am using the two proper ones for video.

Regardless of what the cards are clocked at. Even underclocked. Having the EVGA in the first slot always caused the blue artifacting when running sli. Fine when not running sli.
Regardless of what the cards are overclocked too. Having the BFG in the first slot never causes this artifacting. My computer will just freeze up when I go to far. But still not artifacting.

Has me puzzled.