Simple Overclocking/Heat Question

ToejaM · 19 Jul 2011 at 14:36

Basically, what influences the heat outcome of a CPU overclock?

Purely how many volts you put through the CPU?

Or if you put say 1.25v though the CPU and set the multiplier to 40, would the heat be different than that of say a multiplier of 44?

My goal is to obviously get the best overclock with the least heat, tis why I'm asking

SeraphX · 19 Jul 2011 at 21:49

all depends on the processor in question,

you can set the multi as you wish on all processors FYI,

but as far as heat goes, for the most part yes, it is generally down to how much voltage is running through the chip, more = more, for much higher voltages you will need much better cooling

personally, i've only ever used Amd chips, my current chip had 1.6v ran through it under water for benching at 4.5Ghz, ( cpu max safe is 1.55v )
but every chip has different limits and max temps to watch out for.
Best tip would be, dont go crazy if your not sure and your cooling is not up to the job

Jokester · 19 Jul 2011 at 21:51

The two things that affect heat are voltage (the big one) and clock rate (not such a big effect).

joeyjojo · 19 Jul 2011 at 22:21

According to intel some years ago:

P = C * f * V^2

where C is the capacitance, f is the frequency, and V is the voltage.

The multiplier itself isn't creating heat, just the resultant clock rate. ie. 400*8 and 320*10 (to use older cpus as examples) would both make 3200 MHz, so the same temps. The power goes linearly with clock speed (double the MHz = double the heat).

The voltage however is quadratic (squared). Double the voltage = FOUR times the power. Which is what Jokester is hinting at.

The above is all only approximate, presumably.

ToejaM · 20 Jul 2011 at 11:23

Cheers for the replys people!

Both me and my girlfriend have the same mobo/cpu/ram - the difference is our cases, psu and gfx cards

Her overclock: 1.175 @ 4Ghz / Idle: 40 / Prime95 Load: 75 @ 1hr
My overclock: 2.25 @ 4.4Ghz Idle: 30 / Prime95 Load: 62 @ 1hr

I know those are safe temps and even at 80 they'd be safe but tbh, they won't reach that high I doubt in normal games, especially the games we play. I don't really want them that high anyway as the room is quite small and gets warm very quickly, as a result the radiator is perma-off! lol though I cleaned out my PSU and now its no longer kicking out warm air with the new setup.

Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor
OcUK GeForce GTX 460 OC 1024MB GDDR5 PCI-Express Graphics Card
MSI P67A-C45 Intel P67 (Socket 1155) DDR3 Motherboard - (Sandybridge) ** B3 REVISION **
Corsair Builder Series CX 430W V2 ATX '80 Plus' Power Supply
Xigmatek Midgard Midi Tower Case - White
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz
Arctic Cooling Freezer 7 Pro Rev 2 CPU Cooler

vs

Intel Core i5-2500K 3.30GHz (Sandybridge) Socket LGA1155 Processor - OEM
MSI P67A-C45 Intel P67 (Socket 1155) DDR3 Motherboard - (Sandybridge) ** B3 REVISION **
Corsair XMS3 4GB (2x2GB) DDR3 PC3-12800C9 1600MHz
Arctic Cooling Freezer 7 Pro Rev 2 CPU Cooler
Cant remember the PSU I have actually, I'm sure its an 850w though.
5770 MSI Lightning 1gb
Antec Lanboy Air

Will be pushing the overclocks slowly and when I have a bit more time. I reckon I could get more out of mine easily at that voltage so I'm gunna give it a go.

I'm happy hers is on 4ghz for the moment, if we start playing anything else thats a bit more demanding and it looks choppy I'll have another look at it but if its that bad.. I doubt a .4-6ghz OC extra will do that much good though.. but then again on 4cores.. perhaps so!