What wattage psu should I need?

I have a new build that has been experiencing mostly random freezes. After troubleshooting every single component I swapped out the 750w psu to a spare Antec 620W I had. That seemed to stop the freezes so I may be in the market for a new PSU.

Should I stay with the 620w or do I need one with a bit more umph?

MB - Asus P8P67 LE Rev 3
CPU - i5 2500k
GPU - 1x XFX Radeon HD 6850 1GB (in the future I'd like to set up CrossFire)
Mem - Corsair Vengeance 1600Mhz 2 x 4 GB sticks
HDD - 2x Hitachi 500 GB SATA II drives
Optical - 1 DVD+- RW
1 PCI Wireless NIC card (Linksys, not sure of model number)

I run a couple usb devices but they tend to be on an external hub with it's own power.
5 answers Last reply
More about what wattage need
  1. What brand was the old PSU? Antec is good quality, but many generic brands flat-out lie about the wattage their units can supply.
  2. Both Antec 620's are rated at 48 amps at 12 volts.

    i5-K - 10 amps
    6850 - 10 amps

    That is 240 watts. Figure another 100 watts for motherboard and RAM. 40 watts for 2 hard drives and an optical. High side estimate of power xconsumption is 380 watts. Add a second 6850 and you are around 500 watts.

    A 620 watt Antec would be fine for XF'd 6850's.

    I say that 380 watts is a high side estimate because one of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 - a card with higher power requirements than yours, a Gigabyte EP45-UD3P motherboard, 3 hard drives and an optical, and a Soundblaster card all powered by a Corsair 750TX.

    Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% PSU efficiency, the system pulls 300 watts from the PSU.
  3. The old psu was a Coolmaster. I got it a few years back and it's been running fine as far as I could tell. Still stress testing the Antec, but so far it seems to be performing really well.

    I really appreciate everyone's replies.

    In case anyone is curious http://www.newegg.com/Product/Product.aspx?Item=N82E16817371048 < That is the psu I have
  4. Coolermaster normally make decent PSU's, but this is not the first time I've heard of one going bad. Happened to my brother as a matter of fact.
  5. As your system is doing good with your Antec 620W, then you´d stick with it, even when you decide to Firecross your HD 6850.
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