View Full Version : Dual 7800 GTX SLI problem

10-03-05, 06:57 PM
I am having a problem with texture tearing and flicker when I run my 7800GTX in SLI. Both work fine when they are running by themselves. Here is my system specs:

AMD 64 4000+
OCz 2GB platinum DDR ram
Asus A8N-SLI premium mobo
2x evga 7800 GTX
2x SONY DVDR Drives
raid 0 2x WD raptor 74GB 10krpm HD
1x WD IDE 120GB drive
SB live Gamer
enermax 600w SLI certified PSU

I tried the 78.01 and 78.05 drivers with no luck
Mobo BIOS flashed
installed latest Chipset drivers 66.6

when running in SLI Vsync doesn't work. Vsync only works when I am running one video card only. I used speedfan to log my voltage during a 3DMark05 run and and voltage drops from 11.77 to 11.65 according to the Speedfan reading. I disconnected all the stuff that I don't need to to try to increase voltage and I got 11.84 at idle but it drops to 11.71 when running a benchmark. Still same problem. what do you guys think? I am going to get a voltmeter and test the rails with it. Maybe my BIOS is reporting wrong voltage reading.


10-03-05, 07:10 PM
V-sync currently only works in some games/in some SLI modes. I don't think it works in AFR mode but is supposed to be changed at some point to work in all modes. I have no idea about what could be causing the issue you're having though.

Edit: If you don't mind using betas, the 81.82s are working well for me and they allow you to enable/disable SLI on the fly without having to reboot. Unfortunately, it doesn't look like the planned v-sync support for all modes is in this set so it won't help in that respect.

10-03-05, 07:15 PM
It is ok if I can't get Vsync to work in SLI. At least I want to fix my texture tearing and artifacts problem.


10-03-05, 07:42 PM
Triple Buffering might help your tearing problem. As far as artifacting, that could be only pointing to overheating or your card being defective.

10-03-05, 08:56 PM
I ran 3Dmark05 and kept an eye on my GPU temps. GPU 1 runs at 66C and GPU 2 shoot up tp 73C. The case was open too. Why does GPU 2 get so hot? I will test them 1 a time and see if temps are any different.


10-03-05, 09:32 PM
After all the testing i've done. I am pretty sure I am getting this flicker due to the drivers not allowing Vsync when in SLI mode. Hope they release a driver that does that soon.


10-03-05, 09:46 PM
You should be able to verify that by trying some of the games where v-sync works. Look for ones using SFR mode. Also, I'll see if I can find a few examples of where it works. That should at least tell you if that is the issue you're having.

Edit: Here is the list the last time I checked on this but I'm not sure it'll be the same now. In general, AFR is the best mode for SLI (most benefit) and if nvidia has added profiles since I checked last and changed the mode to AFR, then some of the ones I list may not work now. I also don't know the driver version when I checked but it was 7x.xx something (although, that doesn't help a lot I guess since there are several 7x.xx drivers). :)

BloodRayne 2
FEAR (sometimes locks)
Far Cry
Unreal 2
Star Trek Elite Force II
Max Payne 2

Doesn't work
Lego Star Wars
Half-Life 2 / Counter Strike (although, I think SH64 said it works for him)
Boiling Point

10-04-05, 09:50 AM
73C is kind of high, i dont think my 6800u's in sli even got that high under load, but i may be wrong.

10-04-05, 06:03 PM
Yup I am having the Vsync issue. Far Cry runs perfect in SLI. I guess my only option is to wait for drivers. I just tried the 81.82 but they don't support SLI Vsync yet.