PSU requirements or suggestions 6870 Crossfire

I am building a new system and don't really know what PSU I should be getting. I am currently looking at the Antec EarthWatts EA-650 GREEN 650W power supply. Using the Thermaltake Power Supply Calculator, it looks like I'll need just above 600 watts, but I'm not sure about Amp requirements. The computer will be used for gaming and graphics/cpu intensive programs. I'm on a pretty tight budget, but any suggestions are helpful and much appreciated.

- i7 2600k (OC from stock 3.4 to 4.0)
- Gigabyte GA-Z68X-UD4-B3 MoBo
- 2x G.SKILL Ripjaws X Series 8GB (2 x 4GB)(16GB total)
- 1x Seagate Barracuda 1TB 7200 RPM HDD
- 2 AMD Radeon 6870 Crossfire X
6 answers Last reply Best Answer
More about requirements suggestions 6870 crossfire
  1. Where are you buying from, how much is the current Antec your talking about?
  2. A good 650W PSU will be plenty for a system with two 6870s. However such a system also needs four PCIe connectors, unfortunately most 650W PSU only come with two. You could use peripheral to PCIe adapters if you are happy to use them.

    Assuming you are in the USA and buying from newegg, these are some PSUs which do come with four PCIe connectors:
    XFX Pro 650W Core Edition 80Plus Bronze $90 ($10 rebate, $6 shipping)

    Xigmatek NRP-PC702 700W 80Plus Bronze $75 ($10 rebate, $2 shipping)
  3. Cygnus x-1 said:
    Where are you buying from, how much is the current Antec your talking about?

    I would most likely be buying from Newegg or Tigerdirect. and the Antec is currently $54.99
  4. Silvune said:
    Xigmatek NRP-PC702 700W 80Plus Bronze $75 ($10 rebate, $2 shipping)

    I haven't heard of Xigmatek before. It has an 80+ bronze certification which is nice, but is this a well trusted brand? Would it be better to get a 700 watt system with 4 PCIe connectors that might be the same price, by a "more recognized" brand name?
  5. Best answer
    Although a 650w unit is good for crossfire 6870's, the fact that your're also overclocking your CPU (and most likely the gpus) means that your going to run nearly 70-80% of the PSU's capacity under load. In that circumstance, i'll recommend you go towards the 750w units just to get some breathing room for yourself.

    Heres a few 750w units i recommend...

    Corsair TX750M

    XFX Pro 750

    Corsair TX 750 V2

    Corsair HX 750

    Antec HCG 750

    Antec New Blue TP 750

    Antec EA 750

    Seasonic X650
  6. Best answer selected by BME554.
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