Tri and Quad Crossfire Power Consumption

Considering getting another 3870 or 3870x2 for crossfire x setup.

I have this PSU http://www.newegg.com/Product/Product.aspx?Item=N82E16817171031&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-RSSDailyDeals-_-na-_-na&AID=10521304&PID=3463938&SID=

I'm also running 4 120mm fans, one 80mm fan, 2 40mm fans on my gaming harddrive, 2 7200rpm harddrives, one 3870x2, and 2 dvd drives.

Wondering if I could add a 3870 or 3870x2 without needing a PSU upgrade?
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More about quad crossfire power consumption
  1. I don't think you could get away with adding another 3870.

    Check out the fine print on your PSU - the part where it says shall not exceed 431.5W


  2. I already greatly exceed 431.5 watts with no problem.

    Unfortunately that means I'm already pushing my luck on power.

    Anybody else got input?
  3. Here is a tested tri and quad 3870 power chart. You can find the rest of the system specs here.
  4. stonedzen said:
    I already greatly exceed 431.5 watts with no problem.
    You may be pulling 430+ AC watts from the wall socket but still be under the 431 DC watts the PSU says it can supply.
    If your PSU is 75% efficient and pulling 500watts at the wall socket it means your draw on the PSU is about 375 DC watts.
  5. WR2 said:
    You may be pulling 430+ AC watts from the wall socket but still be under the 431 DC watts the PSU says it can supply.
    If your PSU is 75% efficient and pulling 500watts at the wall socket it means your draw on the PSU is about 375 DC watts.



    way over my head there, but I'm guessing you are backing up the opinion that it wont work?

    What is the worst case scenario, will my rig just not boot up?
  6. You could possibly boot up with with quad X2s. See the idle power in the chart above?
    But remember, thats on a different system and probably using less power than yours considering your extra fans, HDDs and DVD.

    If it were my hardware I'd never try it.
  7. okay, but again whats the worst case scenario? will it damage my system?
  8. OK I know the max load for the VRM on both cards.

    3870 :105w
    3870x2 :196w

    The average load at stock clocks is usually less either wise there would be no oc room. Typical load for a single 3870 is 85w which is the same for a 8800/9800gt while I can only guess the avg load for the 3870x2. 160-180w total draw for a 3870x2 under load at stock clocks.
  9. Worst case scenario, it blows up, sends a current spike through the system burning out every component. Likely scenario, it trips its internal breaker and automatically shuts the system down.

    Also realize that triple and quad fire scaling arent nearly as good as 2 way crossfire scaling. How much does another 3870x2 cost? You may be able to sell your current one off and get a 5850 instead which will do better.
  10. I'm trying to trade for the 3870/3870x2, though I may spend up to $100. I never spent anything on my first 3870x2 as it was a gift, so spending a little money isnt a huge deal for me...though I am on a budget.
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