Which Size Power Supply?

Hi everyone. I'm about to upgrade my PC but I'm not sure whether to purchase a 850W or a 750W power supply. The new PC specs are:

CPU: i5 2500K
Graphics: ATI 6970HD
Mobo: Asrock Z68 Extreme4-Gen3
RAM: 2x4GB Ripjaws X G Skill (1600Mhz)
SSD: OCZ Vertex 3 120GB MAX IOPS
HDD: 1 TB Hitachi (not quite sure which model, but nothing too fancy and it's not green)
DVD: Liteon DVD-RW Drive

Can someone please let me know if I can use a 750W power supply or if I should buy a 850W one instead?

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More about which size power supply
  1. 750 is more than enough. I run a 750 on a similar sys with 2 ssd, 3 hdd and 2x6870. Look for at least bronze cert and do a search on the ps. If you are lucky someone will have done a review.

    Modular is another very serious choice as trying to get rid of unused cables so as to not impede air flow is a pain.

    I can't remember who won the single vs dual rail debate. Single I think.

    One other idea is a ups. nothing kills pc's faster than spikes, drops, brown and black outs. I saved up so mine has sine wave correction. My pc recieves stable clean power no matter what the power company does.

    If you want future proof than make the jump to 1200w. Quality over quantity with ps.

    Hope this helps.
  2. The 6970 only requires a 550w psu, which should be plenty. With a 750w (or an 850w) you'd be set so that if you ever decided to get a second graphics card for crossfire, you'd be set. You can get a Corsair tx850w for about $125 after rebates, which is about double what a good 550-600w psu would cost. Spending a few extra dollars in the psu department (without going totally overboard) isn't a bad idea.
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