Prescott fan & heatsink question

HoboRandy · Post by **HoboRandy** » Tue Dec 07, 2004 10:28 am

Hello! I've been reading articles and threads on this site for over a month, and it's a great source of info. I do have a question on my mind that I was hoping someone could answer.

I am putting together a new system, and I have decided to purchase a Pentium 4 3.0 530 (Prescott core). I understand these to run very hot. Every article that discusses performance tweaking and overclocking indicates you need a new cooler. Every article that talks about silencing your computer indicates you need a new cooler.

Well, what about those of us who won't be overclocking, and don't need an absolutely silent computer (it sits in a compartment under my desk anyway)? Is the stock fan & heatsink from Intel going to keep my CPU in a safe operating temperature, even under load? I work in Photoshop and Illustrator professionally, and I'd probably be tempted to play some games since my computer will support them. I was planning to use the Antec 3700BQE case and included power supply.

Thanks!

burcakb · Post by **burcakb** » Tue Dec 07, 2004 1:27 pm

HoboRandy, WELCOME TO SPCR !!!

Let's do some calculation.

According to CPUHEAT & CPUMSR

When there is no overequipped cooling solution, a stress test software causes CPU to overheat. Under such conditions some of Intel processors slow down to prevent CPU core destruction by heat. They generate what is known as duty cycles, therefore decreasing computation performance.

The processor you describe uses about 100W at full load. Though an equivalent AMD Athlon64 is rated for 89W, practical experience suggests that its power draw is less. That's 11W difference at least. 11W that first your CPU cooler has to take away from the processor and second that your case has to exhaust out. Considering that Athlon64s undervolt extremely well, I'd say it's possible to reduce the power draw of an equivalent Athlon64 by about 30W. In total that makes 41W. That's nearly half the heat of the P4 you chose. (Take care, this is not an apples-to-apples comparison as I have no idea of how well the prescotts undervolt. Still it should give you an idea)

If you're aiming for a quiet computer, you need to run your fans etc slower so they don't make noise. Evacuating half the heat is much easier.

Coming to your question, will the stock cooler work? I'd say yes. Photoshop & Illustrator won't load the CPU to its maximum. Still the P4 is a hot chip even at idle so the fan on the CPU cooler will be making a racket cooling it down. A better, more efficient cooler would do the same with a slower turning, larger fan.

I tried to point out how superior the Athlon64 platform is in terms of thermal performance. If you're stuck on P4 AND quiet computing, you'd do well to look at the ThermalRight XP-120 heatsink (for which you'll also need a fan, lots of options there) which somebody once named "Prescott Pacifier"

cansan · Post by **cansan** » Tue Dec 07, 2004 4:48 pm

Friend of mine got the 3.0 prescott recently. And I thought my 3 year old horrible 4800rpm (60mm) cpu fan was very loud!

I could not believe my ears! The noise was mostly (>80%) from the stock cpu cooler. Its not very tolerable unless you are gaming...
His motherboard said it was at 40C after 30mins doom3,

I believe that!!!

HoboRandy · Post by **HoboRandy** » Wed Dec 08, 2004 10:24 am

What about the new Zalman 7700, and an additional 92.5mm case fan in the front of the 3700BQE? Maybe a couple of fan controllers to turn down the case fans if temps allow. Will that be sufficient to keep it safely cool and at least a bit quieter than stock?

halfpower · Post by **halfpower** » Sat Dec 18, 2004 6:02 pm

You should be aware that I'm very much a newbie in this field, but I have been looking into the Prescott chips, and I not the type to overclock.

I read on one site that the Athlon 64 chips had to maintain a temperature below 70C. The P4 3.4 550 Prescott on the other hand only had to stay below 80C, and 80C-70C = 10C = 18F. Another interesting tidbit about the Pentium Four's is that if they start to get too hot, they will automatically underclock. This will prevent the chip temperature from increasing further. Does this mean I can under-fan? I don't know.

As far as power draw goes, one should remember that just because a circuit draws twice as much electricity does not mean it will produce twice as much heat.

Qwertyiopisme · Post by **Qwertyiopisme** » Sun Dec 19, 2004 12:23 am

halfpower wrote:...As far as power draw goes, one should remember that just because a circuit draws twice as much electricity does not mean it will produce twice as much heat.

Well if it draws twice as much electricity and it doesn't turn all of it into heat where does th rest go? I think you meant (Sorry about this if I'm wrong) that 2x the heat power output is not equal to 2x the temps, which is correct, beacuse the hotter something gets the easier it is to cool.

burcakb · Post by **burcakb** » Sun Dec 19, 2004 2:54 am

halfpower I remember pointing this out to you in another thread but P4s run hot to begin with so they NEED the higher temp ceiling. And the 70C for Athlon64 is BS. I ran mine at 80C for nearly an hour with no problems. But I had to do really crazy things to make it go up to 80C like increasing the voltage significantly, overclocking like hell etc. A P4 can see 80C very easily with a stock setup.

And as P4 thermal designs are geared for intermittent loading, putting a long-term full load on it will certainly force the chip into underclocking.

For the record, even though most video editing software is optimised for Intel chipsets, AMD has been making huge dents in this market with its Athlon64.

Also heed qwerty's note. Basic law of physics: conservation of energy. What goes in, comes out.

halfpower · Post by **halfpower** » Sun Dec 19, 2004 6:33 am

Qwertyiopisme wrote: Well if it draws twice as much electricity and it doesn't turn all of it into heat where does th rest go? I think you meant (Sorry about this if I'm wrong) that 2x the heat power output is not equal to 2x the temps, which is correct, beacuse the hotter something gets the easier it is to cool.

The energy can go to ground. It can also leave on the wires it came in on (though this may depend of the wireing). Energy is sent to the hard drive, monitor, and USB/firewire devices. It is also radiated in the form of electromagnetic waves and is transfered into kenetic energy by the fans (wind energy).

halfpower · Post by **halfpower** » Sun Dec 19, 2004 6:42 am

burcakb wrote:halfpower I remember pointing this out to you in another thread but P4s run hot to begin with so they NEED the higher temp ceiling. And the 70C for Athlon64 is BS. I ran mine at 80C for nearly an hour with no problems. But I had to do really crazy things to make it go up to 80C like increasing the voltage significantly, overclocking like hell etc. A P4 can see 80C very easily with a stock setup.

And as P4 thermal designs are geared for intermittent loading, putting a long-term full load on it will certainly force the chip into underclocking.

For the record, even though most video editing software is optimised for Intel chipsets, AMD has been making huge dents in this market with its Athlon64.

I believe that the AMD's do indeed run cooler. I think the a Pentium will give my computer (with my applications) 6% better performance and 20% more noise. I haven't figured out how to properly cool either one of these systems yet.