When do I need to cool mosfets?

OLMI · May 13, 2004

I'm running my processor at 11.5x200 and I want to push it further (it's only at 47 C while priming). I have it at 1.952v vcore. I need to up the vcore and I want to know if the mosfets have anything to do with this? My system specs are in my sig. Thanks

SewerBeing · May 13, 2004

apply the simple rule I use, touch it, if it feels hot slap a heatsink on it (no I am not recommending you take off all your heatsinks and run it and then touch the parts, because you may fry something). If they are not hot, dont bother with a heatsink.

Daewood · May 13, 2004

i agree with sewer being i can usually tell if something needs a heatsink or even a hs and a fan just by touching it

Voodoo Rufus · May 14, 2004

The touch test is time proven, it just works. If you feel it and you can't hold your finger on for more than a few seconds, get some sinks put on.

larrymoencurly · May 14, 2004

Since the MOSFETs are in a voltage regulator circuit that measures their output, why should cooling them to decrease their resistance cause the voltage to rise? Because if the circuit is being run that close to its max (assuming the PSU is feeding enough voltage), wouldn't it be better to do something like install bigger capacitors -- or back off on the clock speed?

I thought that the best reason to cool the MOSFETs was to prevent them from conducting so much heat through the circuit board and into the capacitors next to them.

Maximus Nickus · May 14, 2004

The main reason for cooling Mosfets is indeed to prevent them from conducting as much heat, this increases system stability at higher voltages. Computers do not like excessive heat, and mosfets are no exception, personally I have heatsinks on my Mosfets even when they are reasonably cool, quite often they will heat up significantly when under intense load espicially in summer conditions.

M_N

slater3333uk · May 14, 2004

They will be hot @ 1.9v

Im running my rig at 1.95v and the mosfets are at 80c (mesured from the back of the board!) without any sinks

(im going to watercool em so i dont want to glue sinks on them yet)

HiProfile · May 15, 2004

MOSFETs usually have built-in thermal-shutdown circuitry. While it may be good for saving them, I'll let you guess what it does to system stability when they get that hot...

I know the physical case won't melt (just try melting it with a soldering iron) at any temps you'll get it too. Like I read in some PSU roundup, power circuts place just as much emphasis on maximum power as they do on maximum operational heat. Cheaper PSU's are rated at whatever watts at 25C, whereas expensive PSU's are rated at their 400+ watt ratings at much more realistic 50C+ temps.

Why not play it safe with components that directly feed your CPU?

magick_man · May 15, 2004

my feeling is if it is flat and bigger than a penny and produces heat slap a heat sink on it.

~Magick_Man~

Ad Rock · May 15, 2004

I have the same board as you and I know my mossfets are really hot. I plan on slapping this old heatsink I have on as soon as my artic silver adhesive comes in. I have read several posts from people with the same board as us, and they all reported a more stable Vcore with the mosfets sink'ed and thus a more stable OC.

I say sink it

.

magick_man · May 15, 2004

Ad Rock said:
I say sink it .

i couldn't agree more

~Magick_Man~

CandymanCan · May 15, 2004

Im putting some on right now i have 2 on already, need to cut somemore but whe ni touched the thing's i almost got a blister cuss they were so hot.

OLMI · May 15, 2004

Wow, I'm surprised. I touched what I think are the mosfets on my board, and they weren't hot at all. They're the little black square thingies next to the capacitors by the zif socket, right?

t1mex · May 15, 2004

yes, they are usually arranged in groups of 6... *usually*

OLMI · May 15, 2004

Ok, then I know where they are. I touched them while prime95 was running after running for about 15 minutes, and they weren't hot at all. The wind from my tornado was even blowing on my finger that was on the mosfets. So maybe the tornado is actually cooling the mosfets too?

When do I need to cool mosfets?

OLMI

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