Peltier idle and load differnce in temp

freshy98 · Aug 13, 2001

I am using a 52W Peltier and a good cooler (gonna be better soon) and I was wandering...
Why is the idle temp very low (almost 0C) and the full load temp 45C? That's a difference of 45C!!! Can anyone explain me this?
Is it normal. Should I be scared?
I Have this for a year now, and never had a problem with it, but I was just wandering.

Colin · Aug 13, 2001

With the heat your Celery is putting out, you need a 72 watt pelt. The 52 watt pelt can't handle the heat from your Celery at full load.

freshy98 · Aug 13, 2001

I thought the general rule with a Peltier was that the Wattage of a Peltier should be about 2 times that of the output Wattage of the CPU?

It seems logical that how higher the Wattage of the Peltier, the lower the temp's will be of the CPU...But is that the only solution?

Colin · Aug 13, 2001

That’s the rule. I am guessing your CPU puts out heat in the middle 30 watt range. A 52 watt pelt is going to come up short.

One thing to remember with pelts is you need enough capacity to pull the heat from your chip. Adding any more extra capacity in the pelt is just increasing the heat you must dispose of. The theoretical Delta T of 69C does not change when you add a larger pelt, only the ability to pump more heat. To get a larger Delta T you need to stack the pelts.

freshy98 · Aug 14, 2001

Well, right now I have a Celeron 850 which does standard about 25W tot 27,5W. It's cooled by the 52W Peltier and a GW-FKP32 and a 4500rpm fan (don't know the CFM of it though). The new cooler I have is a Thermalright SK-6 and a 4200rpm fan (untested as of yet, FKP32 fan should be 4200rpm too so the new fan could also be ~4500rpm). Should ~4500rpm be enough on the SK-6 to cool a 72W or 80W Peltier?

Colin · Aug 14, 2001

Sorry if my figures were off. I am not a Celery guy and Radiate is not working for me right now. I'm used to 128 watts of CPU heat, two pelts and H2O. From what I have read and talked about with the real HS gurus, the SK6 should be a dandy cooler for the 72 watt pelt. People have been using a PEP66 to cool 72 watt pelts and the SK6 is a much better HS. Not having used the SK6, I can't comment on the fan.

freshy98 · Aug 14, 2001

OK, I believe the SK-6 is good for it too. But how about the fan? Will a 4200 - 4500rpm fan be enough to blow or suck all the air away? Personally I was thinking about blow thoug since the shroud in my case has it's fan sucking into the case, thus blowing towards the HSF.

JoeC · Aug 14, 2001

The 4500 rpm fan is pushing something like 24 cfm; a Delta 38 is 38 cfm and higher pressure.

If you substitute the Delta, you should see a marked difference in performance.

Your problem right now is you're using a low speed fan in a high heat situation; BTW, I AM NOT in favor of Delta 38s due to their high noise. However, in air cooling with the same heatsink, the more cfms, the better perfrormance.

Note also, however, that performance gains beyond the Delta 38 are minimal and, IMHO, not worth the noise.

IMHO, air cooling peltiers is not worth it.

Colin · Aug 14, 2001

I would think blow but this is an opportunity for you to do some research and report the results.

freshy98 · Aug 14, 2001

JoeC said:
The 4500 rpm fan is pushing something like 24 cfm; a Delta 38 is 38 cfm and higher pressure.

If you substitute the Delta, you should see a marked difference in performance.

Your problem right now is you're using a low speed fan in a high heat situation; BTW, I AM NOT in favor of Delta 38s due to their high noise. However, in air cooling with the same heatsink, the more cfms, the better perfrormance.

Note also, however, that performance gains beyond the Delta 38 are minimal and, IMHO, not worth the noise.

IMHO, air cooling peltiers is not worth it.

Maybe air cooling a Peltier ain't that great, but right now I'm stuck with it due to space on my room. I think I will build a watercooled peltier system in about 2 years, but that I can not garantee.

Also, doesn't the Delta 38 make a hell lot of noise?
I'm thinking of getting a 5700rpm fan. Should do it too. Also, like I said above, the shroud also has it's on fan blowing towards the HSF. So it's basicly helping the fan on the HS?

freshy98 · Aug 14, 2001

Colin said:
I would think blow but this is an opportunity for you to do some research and report the results.

I was thinking the same thing, just asking

But I think I will try blowing first 'cause of the schroud fan direction of blowing.

Peltier idle and load differnce in temp

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