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Discussion: General Forums / Hardware & Software Discussion - SLI help - I think I have the answer for this but I am just looking for verification
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11-13-2006, 03:27 PM #1
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SLI help
I think I have the answer for this but I am just looking for verification so here goes.
I have just purchased a second EVGA 7800GT pci-e 256mb gfx card to run SLI. Everything seems to be fine but when I plug the second card in and restart the system I can't get it to fire. The system has no juice at all as if the power supply wasn't plugged in at all. I have swapped the cards and it has made no difference. Here is the weird part I have one card plugged in with the 6 pin connector and I have left the other card's 6 pin connector off and the system starts.
I am assuming that my PSU isn't big enough to handle SLI. My power supply is 500wts Xconnect. I know of others who have used this same PSU with SLI and have had no issues. The only thing I can guess is that I am running a AMD 754 socket chip which I believe is a bit more power hungry than the 939 socket.
My specs are
AMD 754 3500+ CPU
Epox EP-8npa SLI mobo
2gig 3200 Corsair Twin X mem
2 EVGA 7800GT
1 80 gig hdd
Any help or advice is greatly appreciated.
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11-13-2006, 04:42 PM #2
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Re: SLI help
Have you tried single cards in both of the PCI-E slots already?
|TG-12th| Sawviper
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11-13-2006, 04:50 PM #3
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Re: SLI help
Yes I have sqapped both the cards into the number one pci slot and they both worked in that slot
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11-13-2006, 05:16 PM #4
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Re: SLI help
What about only one card in the number 2 slot?
|TG-12th| Sawviper
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11-13-2006, 05:52 PM #5
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Re: SLI help
Haven't tried that will check and rport back thanks
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11-13-2006, 06:01 PM #6
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Re: SLI help
Do you have to do something in the bios to tell it it has dual cards or a jumper on the motherboard.
The Old Guy
kin3
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11-13-2006, 06:34 PM #7
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Re: SLI help
No not according to the manual. It states I have to avticate the multi GPU but that is windows based and not bios. I have also looked just to make sure.
After trying to run both cards together I ran across the issue of it changing the time and date on my system. It also changed my boot priority from my main sata drive and it changed it to an IDE HD I have in my computer. That tells me that the system is loosing power to the mobo correct? Which brings me back to the PSU being to small?
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11-13-2006, 06:50 PM #8
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Re: SLI help
Yeah, it would be PSU related. If both cards work fine in the slots seperatly, then they aren't the problem. I believe you need a 650w power supply for the cards to run properly. There should be plenty of info on SLI requirements on www.nvidia.com, or at least on the internet as to the exact requirements.
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11-13-2006, 07:50 PM #9
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Re: SLI help
Ditto on acid's comment. If you elimiate the GPU being the problem by trying each separately and then elimiate the PCI-E slots being the problem by successfully using either with a single card, then the most likely problem is the PSU. What brand/power do you have anyway?
-TFTwisted Firestarter
a.k.a |TG| Harkonian
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11-13-2006, 08:17 PM #10
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Re: SLI help
500 watt xconnect
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11-13-2006, 11:54 PM #11
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Re: SLI help
Ultra X-Connect 500W: Only 28A on the 12V rail. SLi will require more than that, I'm afraid.
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11-14-2006, 05:41 AM #12
Re: SLI help
To run dual 7800GTs, you'll need a PSU with a Dual +12V Rails. A single rail is not sufficient to handle the power requirements of two 7800GTs. Preferrably something with 12A on each rail or higher. Or else you might run into problems later down the road (PSU wearing out early, etc.).
Acreo Aeneas
Content Development Team
Technology Relations Manager
Former 9th IHS Member. Long live the mobile infantry!
Novice Audiophile, Technology Enthusiast
"Arrrrgh! This waiting for BF3's beta is driving me up a wall!" - Acreo Aeneas
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11-14-2006, 08:32 AM #13
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Re: SLI help
Thanks for all the help much appreciated
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11-14-2006, 05:48 PM #14
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Re: SLI help
Yeah you need to step up your wattage drizz. I'm using 600 watts myself, and I think I need more power w/all my peripherals plugged in to boot properly.
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11-21-2006, 09:47 PM #15
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Re: SLI help
Hey guys just wanted to say thanks for all the help. I got my SLI running tonight. It was the PSU, I bought an Antec 600watt PSU that is SLI ready and things are running great.
I just put up a 10166 score on 3DMark05 which is about a 3000 point improvement from my original setup
Specs
AMD 3500+ 754 socket CPU
Epox SLI mobo
2 7800GT
2 gig Corsair Twin X memory 3200
Thanks again to all who helped
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