[Resolved] [Kind Of] SLi Mode Corrupt / Distorted Screen

Dec 24, 2004
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I got my SLi bits together but have had little success getting it working properly, I think pictures show it best:

(Sorry about large picture sizes, not got anything install to scale them)

Camera

Note Bottom Half of Screen

Same Here

Fraps Captured Image

Fraps1

Fraps 2


Board is the A8N-SLi Deluxe (BIOS REV 1002), Athlon Fx55, MSI Gf6800GT x 2, 550W PSU

tried:

swapping cards round,
cards individually (fine)
dicking around with memory (dual channel on and off etc)
unplugging all optical drives / fans to free up power
nvidia drivers 69 - 71.20 (no change)
E-Z Plug is in place, E-Z Selector configured for dual cards, SLi connector in both orientations
other apps (HL2) show similar, although seem to implement SLi in another way, as the interferance appears in a different fashion on the screen (flickering on and off, scrolling up / down the screen)

at lower resolutions, the effect is not quite so bad and appears as simply a distortion on the lower half of the screen when the cursor is moved over / there is movement on screen.

In Single card mode everything is fine also

My current thinking is that one of the cards is buggered, but I cant reproduce anything similar with either card on its own. The only other thing I thought of was the the Sli connector was broken, but it seems unlikely.



Any ideas chaps?

ta

Alex
 

mechBgon

Super Moderator<br>Elite Member
Oct 31, 1999
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I'm not ordinarily a big endorser of software voltage/temp-monitoring utilities, but it might be interesting to run Asus Probe and see if it logs significant voltage sags when you're running heavy 3D. You're using a 20-pin ATX plug in the 24-pin fitting, is that a correct guess? :eek:
 

bap4201

Senior member
Oct 13, 2004
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this may sound stupid, and probably is, but do you have "show gpu load balancing" checked in the nvidia settings for sli multi gpu? If so, uncheck it and see if that helps.
 

AristoV300

Golden Member
May 29, 2004
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I just want to chime in and say that is one hell of a rig. Yeah I would check the driver settings, for the SLI tab.
 
Dec 24, 2004
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Originally posted by: bap4201
this may sound stupid, and probably is, but do you have "show gpu load balancing" checked in the nvidia settings for sli multi gpu? If so, uncheck it and see if that helps.

aye it's enabled, get the same effect with it disabled, minus the green divider / overlay lines - I left it on for the pics because it kinda exlemplifiers theres some Sli shenanigans afoot.

not sure if I mentioned, in HL2, the distribution of the 'distortion' (the bit that looks kinda acid trippy) moves across the screen in bands - I presume this is because HL2 operates in a slightly different SLi mode, whereas Farcry spilts the screen.
 
Dec 24, 2004
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Further oddness / observations:

Running a game in windowed mode with SLi results in a perfect picture, no distortion. Switching into FullScreen and the distortion pops back.

(Tested with Eve-Online)

changing the refresh rate, whilst in full screen mode has no effect (well, at lower Hz the effect is less pronounced)
 

FastEddie

Golden Member
Oct 9, 1999
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You do have the four pin molex power adapter connected next to the top PCI-E slot? The square four pin 12v connector is for the processor, not the graphics rails.
 

Tanclearas

Senior member
May 10, 2002
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What is the SLI setting in the BIOS set to? Have you tried a single card in the black PCIe slot with the selector card set to dual? I believe this will set that slot to work as an 8X PCIe slot, and should be enough to do some tests. I wonder if the second PCIe slot is the problem.
 

mechBgon

Super Moderator<br>Elite Member
Oct 31, 1999
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Also, your monitor's plugged into the card in the blue slot, yes?
 
Dec 24, 2004
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Originally posted by: FastEddie
You do have the four pin molex power adapter connected next to the top PCI-E slot? The square four pin 12v connector is for the processor, not the graphics rails.

yeah that's in, the 2 6800GTs are also individually powered too.

 
Dec 24, 2004
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Originally posted by: Tanclearas
What is the SLI setting in the BIOS set to? Have you tried a single card in the black PCIe slot with the selector card set to dual? I believe this will set that slot to work as an 8X PCIe slot, and should be enough to do some tests. I wonder if the second PCIe slot is the problem.

SLi is set to automatic in the BIOS, forcing it 'on' didnt seem to make any difference.

I've run the system in 'dual monitor' mode (both cards in, SLi not enabled, different monitor pluggeed into each card) Neither card seemed to show any glaring errors.

 

century child

Member
Dec 27, 2004
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I think he's implying that the problem lies with the fact that you are using MSI cards in SLI on an Asus board. While this theoretically should work, maybe it's a different story in practice. It would be interesting to see what would happen if you plugged those 2 cards into an MSI Diamond NF4 SLI or got your hands on some Asus cards and used them on your board instead.
 

Digex

Member
Jul 28, 2003
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#1 Make sure your cards are both SLI compatible.

#2 Use the profiles for the game in the nvidia settings. From what Im reading you need to set the profile for the game to work properly every time, there are like 50 supposed profiles. It has settings for SLR and ALR. I heard you can force it also but sometimes it doesnt work for all games. Just my opinion since I dont have a Asus here to test. But most reviewers are pointing out this issue with games not supporting this feature as of yet.
 

JMag

Golden Member
Dec 27, 2004
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I heard elsewhere that the problem stems form the BIOS 1002, use ASUS's update tool on the CD (so you can do it in windows ) and try updating the BIOS.

I am still currently having problems with my A8N-SLI. I finally was able to get windows installed with a single 512mb DIMM ( when I was running in dual channel with two 512Mb DIMMS, it would crash within 1-10mins everytime I tried to install windows )
Once I got it up on 512mb I flashed the BIOS to 1003-004, shut down, then put in the other DIMM and things worked fine.

However, then I tried overclocking and set my FSB to 215 manual, then went into the MAX OC selection and swithced it to 250 ( it turns out when you select MAX OC it will actually raise your FSB to that level)
Long story short, my SATA drive is no longer detected and I cant freakin boot ( i wonder if I killed my drive )
 
Dec 24, 2004
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Originally posted by: century child
I think he's implying that the problem lies with the fact that you are using MSI cards in SLI on an Asus board. While this theoretically should work, maybe it's a different story in practice. It would be interesting to see what would happen if you plugged those 2 cards into an MSI Diamond NF4 SLI or got your hands on some Asus cards and used them on your board instead.

yeah, given the chance I'd probably gone for matching card / mobo, unfortunately the PCI-E cards are freakin hard to get hold of in the UK :-/.

The retailer I use is pretty good on RMAing stuff so hoperfully when they re-open in the new year, if other cards are available I'll take the system in and try a few cards, see what works.
 
Dec 24, 2004
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Originally posted by: NarcoticHobo
Looks like your monitor doesn't like them, have you tried a dif monitor?


Just tried it now, only other monitor I've got is a TFT (so cant go above 1024*1280).

At lower resolutions on BOTH monitors the corruption is far less, and consists of what looks like slight horizontal tearing on active portions of the lower half of the screen AND quite frequent 'glitches' on the bottom half of the screen.

So it doesnt seem to be monitor related - I even tried different DVI->VGA converters, but they made no difference.