Power Supply for crossfire 7970s.

Hey Everyone.

I was just wondering if an AX850 is enough to power my system. Here are my specs.

- i7 3770k (will put on a small overclock) - (4.2ghz)
- Crossfire 7970s (both on small overclocks)
- 2x 120GB Samsung SSD
- H100i CPU Cooler
- H100i Fans (x2 gentle typhoon)
- 120mm Bitfenix spectre pro (exhaust)
- 200mm bitfenix spectre pro.
- 6 fan controller

Anything else that you guys need to know that im powering?

Look forward to hearing replies.

P.S. Will i have more overclock headroom than i previously mentioned?

8 answers Last reply
More about power supply crossfire 7970s
  1. For all of that stuff you should have a 1000 watt power supply. I entered your specs in a PSU calculator and it says you need at least 920 watts, so 1000 would be perfect.
  2. what psu would support my build as well as support sleeved cables (red ones)
  3. maybe the 1200i. The cables aren't out here in AUS for a while, so i'd just re-cable my system then. its only an extra $100 or so for futureproofing. Also, do you guys have any ideas about what is the best 7970 for cooling, as i'll be running two of them, and im looking for a case with a large window (so not much cooling from the side)
  4. what do you think about the Sapphire 7970 OC versions.? - http://www.umart.com.au/pro/products_listnew.phtml?id=10&id2=92&&bid=2&sid=105439

    at $409 each, this makes them affordable for me. PLus apparently the cooling is pretty good. thoughts?
  5. If you are still building the system, you may want to read about the problems of Crossfire first. If you are ok with it, that's cool, but you shouldn't turn a blind eye at it either.


    Those show Crossfire in the multi-GPU setups. I linked those, as they are the first to use the latest beta drivers and a prototype driver, so you can see AMD is working on the issue.
  6. The 670s only have 2GB of ram. And apparently AMD is better for Eyefinity (surround 3 monitors)
  7. Liamrox287 said:
    The 670s only have 2GB of ram. And apparently AMD is better for Eyefinity (surround 3 monitors)

    You can buy 4gb versions if you want the extra room and what is better depends on the games tested. Many people assume Eyefinity is better because AMD started it, but the review sites seem to show both having issues with different games, and with Frame rating being used to test, Nvidia seems to do better with multiple displays by these tests.

    That said, I haven't used either. I just see different reviews, and I see both companies struggle with different games with 3 monitors.
  8. 1. An 850 watter is more than enough. Plugging all ya parts into here, plus some that I added, (i.e Blue Ray, 6 fans, etc,), I come up w/ 679 watts

    2. The HX850 is cheaper and superior (better voltage stability and lower ripple) to the newer AX series. The HX1000 and 1050 however are dogs ... rest of HX line is great.

    the 7970 and 670 battle pretty much to a draw in single cards setups however, as indicated above, I would avoid the 7970 / Crossfire completely for reasons other than lower power draw.


    If ya worried about the loss in memory from 3GB to 2 GB, note that the 670 also comes in 4GB versions. nVidia doesn't do "eyefinity" but it does do 3D surround, Adaptive V-Sync, PhysX and "Light Boost Technology". If those terms are unfamiliar , links below.

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