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Gpu or psu?

Last response: in Graphics & Displays
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May 12, 2009 3:48:33 PM

I'm running:

q6600@3.2ghz g0
asus p5q pro
4gb a-data ddr2 800
250gb wd 7200k
sapphire hd 4850 @ 680/1103
asus 23.4" 1080p
ocz stealthxstream 600 psu
windows 7


I have owned my 4850 for several months, semi overclocked, but running fine with no hiccups whatsoever. i was browsing newegg the other day and saw that i could add a second 4850 to my system for only $101.19, shipped. So of course I did.
i used one pcie 6pin cable for my old card, and a molex 4-to-6 pin adapter for the new card.

The install went fine, but then when I started to play a game (l4d) all maxed at 1920x1080, the computer locked up. The last sound made repeats/stutters and the image stays frozen until i manually turn off my computer.

After the problem occured i tried all of the different drivers available for the 4850, but no luck. I removed the old (working) card and placed the new one in it's place as a 1 card setup. However i left it on the same cable it was using in the crossfire setup. After 5-20 minutes of play, it would lock up, only this time the screen would have no picture, just a big blur.

I then tried it using the cable that worked with the old card, and encountered no problems when gaming. However when i would open a movie in windows media player 12, it would freeze after ~5 seconds.

I have the old card back in now, and windows media runs without freezing, games run fine.
It sounds to me like the new 4850 may be bad, but the switching of the wires caused me to think that maybe it's an issue with my power supply. Any help would be greatly appreciated. I just want to know if i need to rma this card or buy myself a new psu.
thanks.

More about : gpu psu

May 12, 2009 4:54:26 PM

I realize I have my own PSU question in another post here, but I think I can offer some advice.
If you used the molex adapter to feed the other card I can say this is definite sign of not enough power. Unless you have a massive amperage 12V rail.
But its also tricky to tell if your new card is in fact no good.
But, seeing how your able to run peachy with the old card, same power cord, but not when swapping out just the card(with the WMP exception), there may be a problem with the new card.
I don't wanna say it but perhaps when your PSU overloaded (crashing your PC) perhaps it did some damage to the card or the PSU, or both.

Either way I would definitely invest into a PSU that has the correct number of PCI-E connectors. Unfortunately I don't think you have much of a choice about that if you plan on keeping the CF setup though.

Also if your lucky enough to know someone, or have any pc laying around with a PCI-E slot, try and ATITool cube/stress test the cards. IF there's anything wrong with the video, that test will show it.
May 12, 2009 6:54:47 PM

So I downloaded that AtiTool and ran the stress test on the new card in my system (with the original pci-e cable).
20 minutes strong and not one problem, I think I'm going to get a new PSU and put this all behind me.
even overclocked to 680/1103 it ran 20 minutes @ 99.8% usage with no problems. Never went over 60c.
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May 12, 2009 7:01:43 PM

600W should be plently to run 2 4850's, you could run 2 4870's on that amount.
May 12, 2009 7:16:45 PM

i agree, 600w should be enough.

the molex was never meant to power a videocard, just a thought. the rail that your molex is on might be terribly underpowered for what you are doing.

are you sure you dont have another 6 pin in there somewhere? my 500w psu has 2 6 pins.
May 12, 2009 7:23:38 PM

The specs for your PSU here say that it should have:
Connectors:
1 x 20+4-pin ATX
1 x 4+4-pin CPU (supports double CPUs/supplies stable voltage)
1 x 6-pin PCI-E
1 x 6+2-pin PCI-E

3 x SATA
5 x Peripheral
1 x Floppy

Those 2 connectors should be the ones you use to power the graphics cards.
May 12, 2009 7:28:28 PM

Yeah but they're on the same wire. I tried that from the start and incountered the same problems. The psu has 4 x18amp rails, so I thought maybe by changing wires I would be changing to a seperate rail and maybe get more consistency.
May 13, 2009 3:04:21 PM

Alrighty, just for absolute certainty, you connected up each card to the PCI-E (6 pin) connectors and still ran into issues? If thats the case the PSU has got to be the problem.(not new card, not drivers) And with the Amperage per rail I don't believe it to be a insufficient power issue. After all the 4850's aren't that big a powerhog. Perhaps just a faulty PSU...I would see if its still in warranty for kicks.

Good to know though that the new card is fine, 20 minutes on the fuzzy cube is a pretty rugged test.

Also, did you try setting you CPU back to stock speed with both cards in?

May 13, 2009 4:50:49 PM

Problem solved.

Another guy told me about this windows7 driver. Installed that and good to go. I had a previous win7 driver installed, but I guess it was a different/non functioning one, lol. As for freezing in left4dead...it's an issue with multi-core rendering, so i disable that and it's better as well.

Thanks for all your help, I love this new little cube test lol.
!