Noob question about PSU's and overclocking CPU/GPU

frenchy0312

frenchy0312

frenchy0312

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21 May 2010
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Forgive the noobish nature of this question. If you overclock both your CPU and GPU without changing any voltages from stock they still use more power right? My next question is do you think my coolermaster extreme power plus 550w PSU is capable of powering an AMD 955 BE @ 3.6GHz and my XFX HD5850 @ 850/1200 using stock voltages for both? thanks
Rest of specs below:
Sapphire PC-AM3RS790G 790GX
2x2GB Crucial DDR3 1333Mhz
Zalman Performa Cpu cooler
Zalman VF3000A Gpu cooler
Samsung F2 1TB HD
Sony DRU-860S DVD-RW
 
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Yes, if you increase the clock speed the chip will take more amps at the same voltage because the transistors are being forced to switch faster, which is kind of like rubbing sticks together! The only point of raising the voltages is to enable the clocks to be run even faster, so it is not really optional anyway, the two go together (though there may be enough headroom to raise the clocks a little without raising the voltage).

I do not know if 550w is enough for your setup, but I would think you would be OK in a single graphics card build. I hoped instrumented PSU's would catch on, but they still seem to be rare. I bought a Gigabyte Odin a few years ago which has a USB connection and reports watts, amps, volts and temperature using a little app. Very useful to see exactly what is happening with power on your system. You need to be careful, because as well as the headline power figure there will also be per-rail limits. For example the 800w Gigabyte is only drawing around 300w max on my system, but there is a sub-limit of 180w on the combined 5v and 3.3v rails and it is within a few percent of hitting that.
 
550W will be capable of running that system and with a little headroom of around 100-150W at full loading.

Overclocking the GPU will increase power usage but not dramtically enough to compromise the headroom too much.
 
Uh, there's a bit more to it than that. Overclocked processors (and graphics cards) are running at tighter tolerances than they are at stock. They're less tolerant of dodgy power. At least that's the consensus, and it seems logical enough. In this case I agree with the above, I think you'll be fine too. Overclocking with a £30 psu would be likely to end badly though.

I'm not sure I rate that article by Tom very highly either, my 920 @ 4ghz with two 8800gt's uses 370W DC under load, so 450W ish at the mains. 300W sounds rather low.
 
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