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Looking for a PSU recommendation for my new build

lufiazlufiaz HCM CityPosts: 105Member Uncommon

Hi, I'm looking for a PSU for this PC build:

Asrock Z77 Extreme4

Core i5 3570k, planning to OC to 4k2.

2 x Sapphire HD 7870 OC

2x4G G.Skil Ripjawx DDR3 1600

Creative SB X-Fi Titanium sound card

Samsung 830 256G SDD and my old WD 1TB HDD

5 LED 120mm case fans

My current PSU choice is a Seasonic X 650 gold http://www.newegg.com/Product/Product.aspx?Item=N82E16817151088. Is it good enough? Is there any headroom left in case I want to OC my 2 7870's to 1150 - 1200 ?

Thanks in advance.

Comments

  • QuizzicalQuizzical Posts: 14,763Member Uncommon

    At stock speeds, you'll stay under 500 W in power draw, so you'll be fine.  If you want to heavily overclock everything, it could get dicier, especially if you're going to raise the PowerTune caps on the video card so as not to immediately throttle back your overclocks.

    I'd recommend getting a single Radeon HD 7970 GHz Edition over two 7870s in CrossFire, however.  The CrossFire setup could perhaps be better if you're only ever going to play really big name games that AMD will specifically optimize CrossFire for--and never going to play them near launch, before the CrossFire profiles are ready.  But a single card will be a lot more reliable.

    There's also a question of whether you actually need a discrete sound card.  Most people don't, so I'd ordinarily recommend trying the integrated sound first, and only buying a discrete card if that's not good enough.  But if you're a serious audiophile with a speaker system that costs more than a lot of entire computers, then have at it.

  • RidelynnRidelynn Fresno, CAPosts: 4,160Member Uncommon

    Well, the CPU is 77W (double that for over clock), the GPU's are 130W each (x2 for CFX, x2 for over clock), and then 100W for everything else.

    =774W

    650W could be tight. Over clocks don't necessarily use double power, but each piece of silicon is going to be different, and OCing can really affect power use.

  • QuizzicalQuizzical Posts: 14,763Member Uncommon
    Originally posted by Ridelynn

    Well, the CPU is 77W (double that for over clock), the GPU's are 130W each (x2 for CFX, x2 for over clock), and then 100W for everything else.

    =774W

    650W could be tight. Over clocks don't necessarily use double power, but each piece of silicon is going to be different, and OCing can really affect power use.

    The default PowerTune limit on a Radeon HD 7870 is 190 W.

    http://www.anandtech.com/show/5625/amd-radeon-hd-7870-ghz-edition-radeon-hd-7850-review-rounding-out-southern-islands

    That's perhaps a little high as a way of predicting power consumption.  But they could easily pull more than 130 W under realistic gaming loads at stock speeds.

    (For what it's worth, before I looked it up, I thought it was 175 W, so I was wrong, too.)

  • RidelynnRidelynn Fresno, CAPosts: 4,160Member Uncommon

    I was thinking he said 7850 for some reason - your right about TDP on a 7870. I would definitely say 650W is not enough in that case...

  • LostHawkLostHawk BrusselsPosts: 52Member Uncommon
    Originally posted by lufiaz Is it good enough? Is there any headroom left in case I want to OC my 2 7870's to 1150 - 1200 ? Thanks in advance.

    No, I built a SLI system also with OCed i7 and my 1000w PSU didn't survive it ;) , heavily OCed (under water) and not the best PSU for a SLI system...

    I use a Corsair AX1200 now and I don't regret it. The price is high and there are some other choices but I like the "single 12v rail" which missed on my previous PSU.

    Don't be cheap on the PSU, it's important for system stability, you don't have to buy the high end ones though, but I still like to have around 1200w when using SLI/CrossFire in my case.

  • Four0SixFour0Six Missoula, MTPosts: 1,181Member Uncommon
    Originally posted by LostHawk
    Originally posted by lufiaz Is it good enough? Is there any headroom left in case I want to OC my 2 7870's to 1150 - 1200 ? Thanks in advance.

    No, I built a SLI system also with OCed i7 and my 1000w PSU didn't survive it ;) , heavily OCed (under water) and not the best PSU for a SLI system...

    I use a Corsair AX1200 now and I don't regret it. The price is high and there are some other choices but I like the "single 12v rail" which missed on my previous PSU.

    Don't be cheap on the PSU, it's important for system stability, you don't have to buy the high end ones though, but I still like to have around 1200w when using SLI/CrossFire in my case.

     Overbuilding +1

    I say, if you have to skimp on another part of the build, to get MORE PSU than your calculations say you need.

    A personal issue I ran into is heat. I found that pushing a PSU creates WAY more heat than having a PSU that is "overrated" for the situation. (no shit huh, lol)

    Good luck on the build, OP

  • CyclopsSlayerCyclopsSlayer Minneapolis, MNPosts: 532Member

    Add up all the top power usages for your system, add 20%, and that would be where to start as a bottom end.

    Most PSU's when they get near their top limit get noisy or a little unstable. So always have extra room under the limits. As well this provides room for you to add more or better components without also changing out the PSU.

  • lufiazlufiaz HCM CityPosts: 105Member Uncommon
    Thanks for the help everyone. I might go with a 7970 OC'ed a bit instead and probably drop the sound card till I get a new 5.1 system. In that case, will this http://www.newegg.com/Product/Product.aspx?Item=N82E16817151095 be enough?
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