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SLI Unstable with 2 x 8800 GTX

Associate
Joined
26 Dec 2007
Posts
58
Lo there, I have a problem with my new system. I have 2 x XFX 8800 GTX extreme installed in SLI on an Asus P5N-T. However, whenever I am running SLI, all my games freeze and crash after about 10-20 mins. This is NOT temperature related, as I am monitoring all temps and things are running cool. All games crash in the same manner, with the screen/mouse totally freezing up, and a high pitched whine out of the speakers. Only a reset of the PC can get me out of it.

As an experiment I removed 1 gfx card and all run smoothly without a crash. I tried using the other single card, and again all run smoothly, indicating both cards seem fine as long as they are run singly.

Whenever I put them in SLI it goes wrong :( Suggestions?
 
Associate
Joined
11 Oct 2007
Posts
134
Location
Notts
Is your power supply upto the job? That would explain why its fine with one and fails with two.
 
Caporegime
Joined
8 Jul 2003
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30,062
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In a house
Could be the PSU isn't up to the job if both cards work fine seperately, or you may need a BIOS update for your board, and have you tried some other drivers as well.
 
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Associate
Joined
26 Dec 2007
Posts
58
Hmmmm. I'm running a Q9450, 4gb Ram, 2 x Samsung 750gb. Wouldn't the gigabyte 800 manage that with 2 x GTX cards??
 

ITR

ITR

Associate
Joined
16 Apr 2006
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140
Location
Tamworth
Is the CPU overclocked ? If so, try running everything at stock speeds, inc both GPU's.

Runnin an SLi setup will put more strain on the CPU than with 1 card alone.
 
Associate
Joined
26 Dec 2007
Posts
58
I'm testing everythimg atm at stock speeds, no OC. I agree that things do seem to be pointing towards a power issue, however the Gigabyte odin 800 should be more than enough for that. Review >> http://www.guru3d.com/article/content/457/9/

this review indicates that this PSU could handle my SLI setup with ease even when nicely overclocked....I'm stumped :(
 
Soldato
Joined
19 Aug 2005
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4,039
Location
Ealing, London
Without trying to sound patronising, have you checked that it's all plugged in properly? I seem to remember something similar when I had a PCI-E plug not pushed in fully.
 
Associate
Joined
9 Nov 2002
Posts
1,068
Location
Surrey, UK
Without trying to sound patronising, have you checked that it's all plugged in properly? I seem to remember something similar when I had a PCI-E plug not pushed in fully.
I've also seen a few posts where the SLI bridge wasn't quite seated firmly and caused issues.
 
Associate
Joined
26 Dec 2007
Posts
58
Without trying to sound patronising, have you checked that it's all plugged in properly? I seem to remember something similar when I had a PCI-E plug not pushed in fully.

I think it's fine. The XFX8800GTX has 2 x SLI bridge connections so I wasn't sure which I was supposed to use (the instructions don't even mention it anywhere) but I have tried it with both the SLI bridges and I think everything is seated fine. But yes, I wll make sure and give it an extended test to see.

Has your motherboard got an 4 pin molex socket for when running an SLi setup

Yup, and the 4 pin socket has it's power plugged in.

Thanks for the suggestions, I will get testing and give it all a try :)
 
Associate
Joined
3 Jan 2007
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341
Location
West Sussex
I am sure this is a great supply but you may want to check with the manufacturer.
A check at SLI Zone for SLI 8800GTX/Ultra only confirms the Odin 1200.
Obviously it may not be an exhaustive list there but worth checking.
 
Associate
Joined
26 Dec 2007
Posts
58
Ok, thanks for that. I've had a good old read around and decided to replace the Odin Pro 800 with A Tagan TG1100-U88 1100w Modular. Hopefully that should be sufficient :) *crosses fingers*

If that doesn't work I may invest in a small nuclear reactor.
 
Don
Joined
7 Aug 2003
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43,042
Location
Aberdeenshire
A 800W PSU should be more than enough for 8800GTX SLI, but saying that it does sound like the extra strain of SLI is causing something to overheat and fallover.
 
Soldato
Joined
17 Oct 2007
Posts
3,688
Hello diblob, the Gigabyte Odin Pro800w is able to provide 62 amps on the +12Volt rail which is more than enough to run an Intel Core 2 Quad Q9450, 4GB of RAM, 2 Hard Drives and a dual Nvidia 8800 GTX system setup.

To give you a rough idea of the power consumption of your system:

A single Nvidia 8800 GTX under load will consume around 175 watts which would equate to 14 amps. Obviously you have two Nvidia 8800GTX in your system which would equal to 28 amps. An Intel Core 2 Quad Q9450 at stock under load will consume around 100 watts which equals to 9 amps. Then, if we add a couple of hard drives into the equation rated at one amp each and then some for the extra head room, the above system is only actually going to be pulling around 44 amps on the +12Volt rail.

Though, the problems that you are experiencing do very much sound like the power supply that you have isn't providing enough power to your system which is strange since the Gigabyte Odin Pro800w should run your system very easily. The only logical explanation I can think of is if your power supply is faulty or that particular unit has problems running a dual Nvidia 8800 GTX configuration.

Ok, thanks for that. I've had a good old read around and decided to replace the Odin Pro 800 with A Tagan TG1100-U88 1100w Modular. Hopefully that should be sufficient :) *crosses fingers*

The Tagan TG1100-U88 1100w Modular power supply will certainly not have any problems running your system, it is actually a bit of an overkill for your system and either the Corsair HX 620W ATX2.2 Modular SLI Compliant PSU or the Corsair TX 750W ATX2.2 SLI Compliant PSU would of been more than sufficient.

Now, once you have received your new power supply unit and have installed it into your system but are still experiencing the same problems then there is all most certainly something else that is causing these problems. If you don't mind, could you possibly post back with the outcome please, thanks. :)
 
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Associate
Joined
13 Feb 2006
Posts
465
Location
UK
The latest 174 drivers do not play nicely with SLi on the G80 chips.

that is my personal experience.

What temps are you getting on the GPUs?
 
Associate
Joined
26 Dec 2007
Posts
58
The answers in order

Motherboard - ASUS P5N-T
Temps on GPU - about 55-60c when using single card, goes up to 75-80c when using 2 in SLI!
I am also running the beta 174 beta drivers, so I can always try a quick backtrack to earlier drivers as a test

I should receive the new PSU tmrw morning, so will crack on and get it installed by Fri evening and post back with results. Thanks again lads
 
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