Will Corsair GS800 PSU be sufficient to power 2x Sapphire 7970 Vapor-X 3GB GHz Edition crossfire

fatboyslim

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Hi,

I am building my new photo editing/gaming PC. I have 2x Sapphire HD7970 GHz Ed Vapor-x 3GB graphics cards in xfire and for PSU I've bought Corsair GS800. So my question is will this 800W PSU be sufficient to power my system effortlessly without any issues? The AMD official site states that a minimum of 850W PSU is recommended. Please suggest if I should use this PSU or try to exchange it for a better one with higher wattage?

I am also concerned because my CPU/mobo combo are also power hungry. I have a 3930K processor and Asus P9X79 Deluxe motherboard. Let me give you my whole system configuration, so that it is easier for you guys to recommend the best PSU for this build.

CPU: Intel i7 3930k
Cooler: Corsair H100i
Motherbboard: Asus P9X79 Deluxe
RAM: 4x 8GB (total 32 GB) GSkill Ripjaws Z 1600
SSD: 120 GB Kingston HyperX 3K as boot drive
HDD: WD Caviar Green 2TB x2 (Total 4TB)
ODD: LG Blu-ray writer
Graphics Card: 2X Sapphire Radeon HD7970 GHz Edition 3GB Vapor-X in xfire
Sound Card: ASUS Xonar Essence-ST
Monitor: Dell Ultrasharp U2713HM 27" IPS monitor 2560x1440
PSU: Corsair GS800 (This is my biggest concern????????)
Cabinet: Cooler Master COSMOS II
KB: Corsair K90
Mouse: Corsair M90
Speaker: Logitech Z906 5.1

So, please help me out here with the PSU I've chosen here guys. I am worried with that part. :( Please let me know if you need any other information to make the best decision. And please reply soon as I don't want to delay if I've to exchange my PSU.

N.B. I've found this on Guru3d which raises my concerns even more. It says -

"Here is Guru3D's power supply recommendation:

Radeon HD 7970 - On your average system the card requires you to have a 550 Watt power supply unit.
Radeon HD 7970 Crossfire - On your average system the cards require you to have a 750 Watt power supply unit as minimum.
If you are going to overclock GPU or processor, then we do recommend you purchase something with some more stamina."


So should I not keep a reasonable buffer amount of power available at my disposal ?

Thanks,
Susmit
 

fatboyslim

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@bigcyso1, so basically you are recommending a 80 PLUS GOLD certified PSU between 850-1000W .. I think this GS800 is 80 PLUS Bronze ..

oops.. i see that u've removed all your suggestions and kept this one only! may i know why? is this pc power 950 silver the best among them? :-o
 
Yeah because i don't think the GS800 will cut it better to be safe then sorry imo.

 

slicedtoad

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-7970 = 270W
-i7 3930k @ 5GHz + mobo = ~250W (this is a slightly hard to measure but should be a slightly high figure if anything)
-Everything else: 20-30W (but not on the 12v lines, so they don't matter)

270*2+250 = 790W on the 12v lines.

PSU: 780W on the 12v rail

So that's a bit close to the limit actually, but it should will work fine. Just don't OC you cpu to 5GHz, lol. ~4.5Ghz will give you far more headroom (that i7 uses about 150W less power at stock clocks so interpolate between 100W and 250W to get a rough estimate of an overclock between 3.2GHz and 5GHZ).

If you decided to buy a different one I wouldn't blame you, but if it were my system, I'd stick with it.
 
It's the cheapest best deal among them.
;)

 

fatboyslim

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:ouch: my goodness .. that's 10W more than what this psu delivers over the +12V rails ... :( that is depressing enough .. would not that lessen the PSU longevity? all the time running above and beyond its normal throughput? And if gpu and cpu are overclocked then it can turn its back on me!!! :??:
 

fatboyslim

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okay .. i see ..
 

slicedtoad

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good. The guru3d one is the v2 and is better. It has 792W on the 12v rail and is bronze rated.


Are you an awesome OCer that needs 5GHz? Otherwise, you are no where near that limit.
And ocing your gpus is not really nescessary. 2 7970s will run that monitor fine.

A PSU should never be run over it's limit but that should be easy to avoid. Running it close to it's limit will make it run hotter and will likely reduce it's life time (could still be a long time). And it still has a 3 year warranty that won't be voided by running it close to load.

Also, those are max load power figures. They usually won't be that high which means that most of the time your PSU will be running at only a few hundred watts.

edit:
but if you're worried, the one bigcyco mentioned would be a fine upgrade. Might even save you a few dollars in electricity. And it should be a bit quieter.
 

fatboyslim

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no.. I would not be pushing my cpu to 5ghz mark .. may be @max around 4-4.3 .. so it seems 800w will cut it but then again there IS a chance that it might be a bottleneck at times probably .. so it is safer and better to opt for something with a higher wattage .. something between 900-1000 W .. am I right?? just 2 be on the safer side .. ????
 

fatboyslim

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yeah .. okay that is what i feel .. a bit worried .. after all all these are expensive components and its better not to risk any one of them .. :(
 

slicedtoad

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For your own peace of mind, it could easily be worth it, it's up to you.

But at 4.3 GHz, you won't be at the limit. You'd even have some gpu oc headroom. That said, if I were building a computer exactly like yours I would have picked a slightly higher wattage PSU. If I was upgrading my hypothetical computer with a second 7970, I wouldn't change the PSU.

Since your PSU is still within the easy return period, swapping it would be fine but not completely necessary.
 

fatboyslim

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hmm .. got your point man .. so its better i swap it with a higher wattage one .. but can you guys recommend me the best option among Corsair/Seasonic/Coolermaster in that wattage range?? dont give too many options please :) makes it harder to choose .. other manufacturers likenzxt/pc poweretc are not available here in india that easily ..
 

slicedtoad

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I'm not sure what store you use but between flipcart and theitdepot the best I can find are these
Antec HCG-900 for 9700 rs
and
Corsair TX850 for 8240 rs

You could go higher if you wanted but the prices are quite inflated compared to NA. The Antec will give you all the power you need plus some nice headroom. The Corsair won't have quite as much headroom but it will still work fine and should allow for everything to be oced a decent amount.
 

slicedtoad

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Anything bronze rated and above by Seasonic, Corsair, Antec, PC P&C, XFX, Thermaltake, EVGA, NZXT, OCZ, Zalman, Cooler Master or Enermax at 900W or higher is fine. Pick whichever is cheapest at wherever you shop or whichever you like the best.
The two he linked are both very high quality modular PSUs. If you can afford that, go for it.
 

fatboyslim

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okie .. got the point ... thanks guys for all your help and time .. i really appreciate and thankful to you all ... :)

now I have one more question .. regarding the graphics cards .. do you think 3GB video memory that the 7970 has will be less to power my dell 27" 2560x1440 monitor?? as far as i know in sli/xfre vid mem do not scale up.. i mean even if i have 2x 7970 with 3GB mem each still in xfire they would not act as 6GB rather it will be 3gb only .. so do u think 3gb is sufficient?? or should i exchange them for the 6gb version of the same card sapphire has?