Heat: CPU, hard drives, fans and power supplies 3

[CoyotePuma]

Okay, I know just enough to get myself in trouble. That said...

I have assembled four desktop PCs, only one does not overheat in room temperature highs of about 28C. The one that remains cool, a service installed the 1.6G P4 CPU with its standard cooler, and it is now five years old. The others, P4's (2.8G (478) and 3.2G (775), idle in the high 40C's, normally operate at 50C+ temperatures and 65C+ at 100% utilization. And, I use Artic Silver cleaner and thermal compound, plus Zalman copper coolers.

I am also a relatively heavy user of hard drives and file maintenance, including defragmentation, is a daily event. Average drive life span average is about 18 to 24 months. That alone is why I went to RAID 5 (four drives). Next step will be a NAS RAID 5 system.

Fans: There is so much air flow through my systems, my office sounds like an airport. The cool system runs standard case fans and power supply. The hot systems run two Panaflo high volumes, plus standard case fans, and Ultra power.

What's the problem? In the response to someone's query, I read that a cheap power supply could be the problem. Now, before investing more money and time into assembling another system, would someone like to relieve my misgivings or should I simply go the NAS and a factory brand name computer?

 

[Johnthephoneguy]

Many things can cause one system to run hotter than another, including the processor itself.

Airflow through the case is important, you can have all the fans you want but if they are working against each other they are ineffective. Make sure you have one fan blowing into the case and one blowing air out not both doing the same thing.

As far as hard drives, I have a 10.00 fan that bolts onto the drive itselve and works great. The drives never even get warm. I went with water cooling because I game alot, my temps after hours of gaming are still in the 31-32c range.

The newer Core 2 Duo's are faster and run cooler with less power. if you are thinking of buying a new one, look that way.

 

[CoyotePuma]

Hi John,

Core 2 Duo: Yes, that would be my next system.

Fans: The two top-mounted 100+ cubic feet Panaflos blow in and the two standard case fans next to the CPU and hard drives blow out of my aluminum Antec P160. That's a lot of air and I can feel the exhaust a foot away.

CPU: What nags me is whether I'm mating the CPU with the Zalman cooler, ie., the right amount of thermal compound, etc. I hate the idea of buying a brand name computer, but this heat problem is getting expensive.

 

[Johnthephoneguy]

It doesnt take much thermal compund. Too much will actually work against you, just the tiniest amount is needed to be effective.

Only a very small amount of Arctic Silver 5 is needed for both the small or large exposed single core CPU’s. The amount of thermal compound needed for a small exposed core CPU would be equivalent to about ½ the size of an uncooked short-grain of white rice. For large exposed single core CPU’s the amount of thermal compound needed would be equivalent to about ¾ the size of an uncooked short-grain of white rice. The rule of thumb here is “a little will go along way”.

The flatter the mating surface of a CPU and heatsink, the thinner the layer of Arctic Silver 5 is required. Stock processors and/or heatsinks with normal surface irregularities will require a layer 0.003" to 0.005 thick as shown below to fill the resultant gaps. (Equal to the thickness of about 1 sheet of standard weight paper.) Properly lapped heatsinks with mirror finishes will only require a translucent haze.

 

[wahnula]

Fans: The two top-mounted 100+ cubic feet Panaflos blow in and the two standard case fans next to the CPU and hard drives blow out

CoyotePuma,

I have had the best results with air cooling when I place the intake fan at the bottom front of the rig (in front of the hard drive cage in your case) and exhaust fans at the upper rear and/or top of the case. Sometimes a ducted fresh air fan blowing in at the processor from the side can help.I had to cut a 'blow-hole' in the top of my case to get problematic hot air between the DVD drives out. This way the heat follows its natural flow upwards. I use an Enermax multi-bay with fan controller to quiet the din:

http://www.directron.com/uc9fatr2s.html

That also comes with two thermal leads. There are numerous products more capable than this it is only used an example. This plus the control on my Zalman CPU HSF keeps my OC'd P4 (2.53 to 2.68) near the thermal range you describe but in near-dead silence. It is totally stable. You don't mention instability, just running hot is not a problem with some units:

http://www.intel.com/support/processors/pentium4/sb/CS-007999.htm#Thermal

and it makes sense late the lowest clock speed runs the coolest. No harm no foul. If it ain't broke don't fix it etc.

The idea of the thermal compound is to use enough to only fill in the imperfections between the bottom of the heatsink and the top of the processor. This is usually around the size of a BB. Then you can spread it around (I use the end of a zip-tie, using your finger in a latex glove or plastic bag also works) to cover the CPU mating surface completely. You do NOT want paste oozing out around sides and possibly collecting dust and shorting components.

I have read articles where system builders lap both mating surfaces until they shine, but the results are just a degree or two, not worth the effort and chance for disaster in my book.

If I had that rig I would rearrange the fans and get a speed controller on them all, back them down until you notice instability. Best of luck and welcome,

Tony

 

[paparazi]

The others, P4's (2.8G (478) and 3.2G (775)

500 series?
Prescott core? 800fsb?

The reason I ask is that the 500 series Prescott's were notoriously inefficient and were very difficult to keep cool.
Later 600 series rectified much of this but the newest Conroe's based on a much smaller fabrication process are better still.
As an example:
My E6600 Conroe is idling at just 28C as we speak and is still fitted with the with stock Intel heatsink/fan, and because Conroe's generate so little heat the motherboard is regulating the CPU fan at around 1,100rpm (the same stock cooler fitted to a Prescott 3.2 would typically spin at over 3,000rpm and have temp readings in the 50's.

As the CPU is the main heat generator in your systems I am confident in recommending a new build based on this core as a cure for your overheating blue's.

Martin



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[CoyotePuma]

Thank you. Every one of you gave me valuable information.

Fans: I'm going to reverse the direction of the case's air flow to out the top though it does give me some concern, negative case air pressure. Those Panaflos are real hungry, might have to slow them down - which, of course, will quiet them down. Sounds like a win win situation, doesn't it.

CPU and thermal compound: You got it right and it's a P4 540 Prescott. I want to especially thank you all as I totally misunderstood the application of the thermal compound. I looked at the thickness of the patch on the standard cooler tried for the same, and yes, there was excess oozing. I'm going to redo it, with AS cleaner and AS5, to a haze - I love that idea of using a glove or plastic bag.

I'll let you know how it all comes out. Thanks again, guys.