Second fan in crossfire will not spin

I picked up 2 of the Sapphire 5870 Vapor-X graphics cards and for the life of me cannot figure out what the issue is that is causing this. The card that is plugged into PCI-E slot 1 works perfectly and the fan spins with no issue, however the card in slot 2 works but the fan will not spin. If I switch the cards around the same thing happens with whatever card is in slot 2. I upgraded from a pair of 4850 cards which worked perfectly and the both fans spun, however these will not. I contacted Sapphire Support and they stated that the fan on the second card would not kick on until the primary card is overloaded. That makes no sense, being that the second card would heat up to around 75c while the primary card would be around 55c under load. My system specs are below:

Alienware 750w power supply
AMD Phenom II x4 955 @ 3.41Ghz
8GB G-Skill DDR2 RAM
Sapphire 5870 Vapor-X @ 900/1300

Any ideas on what could be causing this issue?
7 answers Last reply
More about second crossfire spin
  1. does that power supply have four 6-pin PCI-E connectors? Also, what is the amp value on the 12v rail or rails?
  2. Yes, the power supply has four 6-pin PCI-E connectors and the amp value on the rails is rated at 18amps.
  3. 18 amps is not very much. My Corsair 750TX has 60A on the 12V line... So it might be the PSU's fault like jonpaul37 was getting at.

    Seems like the only reasonable suggestion I can think of at the moment.
  4. I would agree, might want to see if you can try another PSU out, something with at least 52a on the 12v rail or rails, preferably a PSU with one 12v rail.
  5. Yeah it sounds like a PSU problem to me as well so..

  6. Thanks guys, went out to Best Buy and picked up a Corsair 950w supply and they both work great now! :bounce:
  7. glad to hear it Driz, remember, not all power supplies are created equal. That Corsair should serve you well in the long run, you should be able to use it for a long time.
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