Trouble with 4870 Crossfire

Hello all,

The problem that i'm having is with my two, just purchased, xfx HD 4870 video cards hooked up my system crashes as soon as I install the drivers. Afterwards I cannot even get windows to boot up. It will start to boot and then just reset. If it by chance makes it to the desktop it will reboot soon after. No errors just as if I hit the reset button.

I originally thought it was the drivers so I tried multiple versions and the same effect

However, with one card removed the computer runs flawlessly. I want to say it might be an issue with the power supply but I'm not 100% certain. is my power supply. It's a decent enough PS but the issue is that there are only 2 PCI connecters and each card requires two. But, I used the 2 4 pin to 6 pin adapters that came with the card to hook up the 2nd. I know this isn't optimal but would it really supply so little power that the computer can't even process windows? I could understand maybe having issues under full gaming load, i.e. crysis or something of that nature. It's a 12v single rail PS so it's not as if I should be overloading a rail.

I ran out of time so I didn't get to swap the two cards to make sure it's not just a bad card out of the box, but I'm hoping to have some insight when I get home from work. What can I check to see if it is indeed the power supply? Or a possible work around to the solution. I may just end up ordering another PS but I really can't imagine that it cannot support these cards to at least run windows.

Here are the rest of my specs:

AMD Phenom II X3 720 Black Edition 2.8 Ghz

MSI 770-G45 MB

Corsair XMS3 4GB DDR3

and of course 2x XFX HD 4870 1GB 256 bit GDDR5 cards.

Thanks in advance for your time.
5 answers Last reply
More about trouble 4870 crossfire
  1. Sounds like you need a larger output PSU. One card works, two do not. Find a replacement that has the 4 6-pin cables you need.
  2. Yeah that's the easy choice, but they should only take about 350w between the two of them. Just doesn't make sense that it should perform so badly?
  3. use 1 6 pin from the PSU on each card and 1 molex to 6pin on each card. That PSU is good and is plently for 4870 CF
  4. Hmm, I had considered that. I'll give it a go.
  5. Definitely do try that...but as a previous owner of a 4870x2 with a 650watt supply, it did not cut it. The manufacturers spec the power output under ideal conditions. The 4870 consumes a lot of power - in a recent Toms test the 4870 was the highest power consuming board.

    One thing to try is when installing the driver, there are several LEDs on the back of the 4870 that are related to power failure. During driver installation, watch to see if any LEDs light up. That would be a clear indicator the PSU is not up to snuff...
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