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How Much PSU do I need

N

Net

Golden Member
AMD FX-8120
8GB DDR3 1600
AMD 5970 graphics card (overclocked at stock voltage)
MSI 5870 graphics card (overclocked at stock voltage)

I have a corsair 850TX will this do it?
 
5970 requires 8-pin + 6-pin, 5870 requires 2x6-pin, and TX850 provides 4 x 8-pin. So you're set for connectors.

FX8120 TDP = 125W
5970 TDP = 294W
5870 TDP = 188W
= 607W max. +12V load at stock

TX850 +12V is rated for 840W. It'll work... But I wouldn't increase any voltages, not on the GPU, not on the CPU. Even overclocking with stock volts may bring power consumption beyond 80%, I'd prefer to stay below that.

If you want to get the most out of overclocking, sell the TX850 and buy a 1000 watter or 1200 watter. Or, just sell the 5000 series cards and get 670 SLI or something.
 
lehtv said:
FX8120 TDP = 125W
5970 TDP = 294W
5870 TDP = 188W
= 607W max. +12V load at stock
Click to expand...

Not quite. TDP does not indicate a maximum consumption , but rather a design limit. Actual maximum consumption usually is lower.

850W should be plenty, a lot of room for overclocking any one component.
Under most non-artificial loads, your maximum power draw should be around 500W. Using the full 850W shouldn't be a problem either, unless you run full loads 24/7. Then a KW-class PSU might be worth the hassle. Of course, swapping GPU's will probably be cheaper (especially in the long run) and more effective.
 
_Rick_ said:
Not quite. TDP does not indicate a maximum consumption , but rather a design limit. Actual maximum consumption usually is lower.
Click to expand...

How do you measure "actual maximum"? Do you mean actual load power consumption, or maximum load power consumption? Also, the TDP "limit" of a graphics card is frequently surpassed in Furmark even without overclocking.
 
Actual maximum is the maximum amount of power going through the card at stock settings.

TDP should not be exceeded under stock settings, as this would be quite literally "out of spec". Modern graphics cards all do thermal power management, so that TDP will be adhered to.
On the other hand manufacturers calculate/set their TDP in a variety of ways, with no documentation, so basing anything but the vaguest predictions on power consumption on them is pointless. Also, a more-than-two significant digit TDP (like "294") is very suspicious, as it's unlikely two cards will have the same thermal behavior down to the last Watt, when pushing out almost 300 of them.
 
There's enough OC potential in his setup to make the +12V load reach the +12V rating under stress testing... that's not "handling it easily".
 
lehtv said:
How do you measure "actual maximum"?
Click to expand...

ampere-meter and a benchmark?
Or estimation from review values for the components. Some reviewers measure actual power consumption by device, instead of whole system load, so there you can get a ball park figure of what load causes what kind of current draw.

And I'd argue hitting 100% under stress testing is "handling it easily", as stress testing represents the worst possible load. If the worst possible load doesn't cause OCP to kick in, you're fine and dandy.
 
Cutting it very close. Strongly not recommended. May fail in a year or two even at stock.

I wouldn't do that setup without a solid 1000w for stock and 1200+ watts for good oc.
 
Itll be fine, even with mild OCing on the GPU's and CPU. Dont listen to that other guy who says you need a 1200w PSU, he doesnt know what hes talking about because he has a 1300W psu for a single card setup and an I7.
 
It should be absolutely fine.
If you want to check before any overclocking, buy a watt meter and check how much power the system is using stock to get an idea of how much headroom you have.
 
I fail to see how OC plays any factor, since he said "OCd @ stock voltage." What I would make sure is to have a better quality PSU, rather than needing something with more maximum power - something Gold standard or better.

I haven't looked too much into the setup, but I would think that something close to @lehtv initially posted, would be true. With PSUs, it's the rails that you have to make sure you have enough current - pay close attention to the Voltage rails and what amperage is allocated to them. You can buy a 2000W PSU, which still might not meet your requirements.
 
Overclocking, even at stock voltage does increase power consumption but not nearly as much as when accompanied by a voltage bump. Nevertheless, the PSU he already has is plenty. I also doubt there's a 2000watt ATX PSU out there that won't meet his requirments. If there is, I'd like to see it.
 
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aaksheytalwar said:
Cutting it very close. Strongly not recommended. May fail in a year or two even at stock.

I wouldn't do that setup without a solid 1000w for stock and 1200+ watts for good oc.
Click to expand...

Really? A year or two? So you'd bet money it won't live past year 2? Where do you make this stuff up from?
 
vol7ron said:
I fail to see how OC plays any factor, since he said "OCd @ stock voltage." What I would make sure is to have a better quality PSU, rather than needing something with more maximum power - something Gold standard or better.

I haven't looked too much into the setup, but I would think that something close to @lehtv initially posted, would be true. With PSUs, it's the rails that you have to make sure you have enough current - pay close attention to the Voltage rails and what amperage is allocated to them. You can buy a 2000W PSU, which still might not meet your requirements.
Click to expand...

Actually rating isnt a 100% indication of quality. A gold rosewill isnt as high quality as a bronze seasonic, all the rating means is how effecient it will be with pulling power from the wall. When OCing power increases linearly with clocks and exponentially with volts, so its possible to overclock and undervolt and either break even or decrease your power usage, like the case with my 2500K.

TemjinGold said:
Really? A year or two? So you'd bet money it won't live past year 2? Where do you make this stuff up from?
Click to expand...

The funny thing is, that guy is probobly running his PSU so out of spec that he might be degrading his own system with voltage fluctuations because the lines dont have enough stress. (i.e under 20%)
 
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