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CrossfireX / Dual PSU Question

Okay so, in the coming month, I'm going to upgrade a couple components in my computer. Memory, GPU(s), and Motherboard.

I'm running a Radeon HD 6750 right now, it works, but barely. So I wanted to upgrade to two Crossfired 6670s.

Need a new motherboard, yadda yadda, fine. I know I can put it all together, but I got to thinking about power.. Since obviously the GPU's draw power from the Motherboard.

So I have a 500w PSU in my rig at the moment. Im taking a wild guess and saying that it wouldnt run two 6670s? Or would it? (please educate me in this lol)

Then I perused the interwebs to find out that Dual-PSU is possible with an adapter cable. Considering I have an extra 400w laying around, its also viable.

I was thinking, If I can hook up most, if not all Fans/Harddrives directly to the 400w. Aswell as having the adapter with the 500w. Could I safely run my crossfire?

Im thinking 2 PSU's = 900w. 500w is going solely to the Mobo, and about 250w(?) solely to fans and HD's. With 150w just in case everything peaks.

Would this be a good idea? or should I upgrade my PSU to 1kw? Any suggestions/ideas?
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  1. Best answer
    Why not a single 6950/70 (or even a 7850)?

    And a single PSU is the way to go because using 2 PSU's can be problematic (although I've done it myself in the past, I can't recommend doing it for anyone else), but I WOULD recommend just getting a good 550-600W unit. That will be plenty for almost any single card.

    No reason to CF 2 6670's, when a single 6950 (probably even a 6870) would be just as good.

    Also, fans and HDD's aren't very large power draws and DEFINITELY don't need their own PSU.
  2. If you are going to crossfire,you should have at least 600w for the mentioned gpu.
    but it would be better if you upgrade to 1kw.choose psu with good review because even the psu mention 1kw, it's not necessarily provide the advertised power.worst,your rig's life might be reduced to half their life due to erratic power supply. i suggest you find psu with at least bronze quality of power.it can never hurt to have more power at your dispense since you clearly are going to upgrade to a more capable component in the future.In a long term, go for higher psu.
  3. DJDeCiBeL said:
    Why not a single 6950/70 (or even a 7850)?

    And a single PSU is the way to go because using 2 PSU's can be problematic (although I've done it myself in the past, I can't recommend doing it for anyone else), but I WOULD recommend just getting a good 550-600W unit. That will be plenty for almost any single card.

    No reason to CF 2 6670's, when a single 6950 (probably even a 6870) would be just as good.

    Also, fans and HDD's aren't very large power draws and DEFINITELY don't need their own PSU.



    This kinda makes a lot of sense. I was just thinking of a way to use my extra PSU. Since I probably couldn't even get $10 for it.
    And honestly, this whole time I've been set on crossfiring, I havent shopped around for single cards.

    I found this 6870: http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=1241686&csid=_61

    Do you think that would surpass the two 6670's?

    And ill get a 600w along with a new card. As long as i'm going with a single.
  4. I don't know that a single 6870 would surpass two 6670's but it would at least equal them.
  5. DJDeCiBeL said:
    I don't know that a single 6870 would surpass two 6670's but it would at least equal them.


    Well for roughly $20 cheaper, that sounds like a plan to me ;)
  6. Best answer selected by E-Zombies.
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