AMD needs a bigger fan?

[Rookie]

While reading posts about Fic mobos and AMD cpu's I read that AMD processors are typically sold with inexpensive (Oem) heat sink/fan combos. Mine was. On a recent trip to the local ma & pa puter store, they had run out of socket 7 fans and offered a celeron socket 7 fan instead.
The heat sink was tall, but the connector was different. So I cut the wires and by trial & error found that the yellow and black wires were 12v and spliced the fan in this way.
Is a tall heat sink better? One of the stores I shop at said tall doesnt translate into efficient- this guy's opinion was that the fan cant pull in enough air to cool the tall heat sink???
What do you all think? I did apply cheap Radio Shack heat sink compound but I really gobbed it on. Will clean off excess and do it over on all my machines. Thanks for being there http://www.sysopt.com/forum/smile.gif
Rookie

[Axel]

Heat sinks work on the basis of surface area. I.E. - if it has tall vanes, it sounds like it will spread and release more heat. The better you do in moving air through those vanes, the more heat is moved away from the CPU.

It is important that you do not obstruct the air flow with ribbon cables and additional components.

A great example is a case I'm working with now - they added additional drive bays that slot over the CPU and do two bad things - the ribbon cable blocks one airflow path and the drive itself blocks another airflow path.

So - it's a really bad idea to put a drive into this bay and block the air flow.

Also - at the top of the case, they have a mounting bracket for another drive over the power supply.

This hinders the flow of hot air off the board and drives out of the back end of the case ( the chimney ) -

Worry more about the air flow than you do about the fan. - Then worry about the fan.

Also - you'll want to make sure there is thermal paste between the heat sink and the CPU for good conductivity - some manu.'s don't put in any there, but it can drop the temp several more degrees.

[dawgtuff]

Make sure you put the heat sink paste on in a "very" thin layer.Too much actually traps heat.

[theCorvetteDoctor]

Interesting you should mention the low air flow.. Just put together my AMD K6-2 400 and noticed that the fan moves so little air that I can't feel the flow.. The CPU temp goes to 108F in a few minutes, so it's not overheating, yet, in this winter environment.

[Rookie]

Thanks Dawgtuf, I didnt know about the thick/thin heat compound trapping heat in- makes sense!

Thanks Axel, the air flow description also makes sense, I have no covers on any of my machines for that reason, but we have pets so animal dander concerns me. I can see inside and use the compressed air when I see dust collecting.

So I gather the guy saying the tall heat sink is just trying to sell me his (cheaper)brand of heatsink...Not sure I want to use the Celeron socket 7 fans though, I forgot to tape one of the cut ends of the power supply and when I picked up the case to insert a ide ribbon it touched something it wasnt supposed to and the machine wouldnt boot. I left it alone overnight and it booted fine. Was worried there for awhile.
Is there some kind of fuseable device or capacitor to absorb accidental electrical surge?
If I ever use that Celeron heat sink/fan again, I'm gonna find some kind of small 2 piece wire connector that can plug in and unplug for maintanence!
Rookie

[OuTpaTienT]

I use a PentiumPro heatsink on my K6-2 (also used the same sink on my old K6). A heatsink is just a hunk of aluminum (can be copper or other conductive material). As long as it fits where you need it, and it makes good contact with the CPU you should be ok.

I had to alter my heatsink because it had a raised rectangular area of the contact side to match the rectangular shape of a PentiumPro. I just took to my buddies cabinet shop, put it on the belt sander and sanded it flat. Then use a succession of finer and finer sand paper grits until it was smooth as glass. It's a little oversized for my CPU, but it works great.

[Crahl]

another interesting point to note, if you use OEM fan and heatsink combos try to ensure the fan is powerful enough. for AMD processors above 400MHz, it's advisable to get fans that run at about 4 to 5000rpm as many cheap OEM fans run below 3000rpm which often doesn't draw enough heat away from the faster processors especially the 500MHz ones.

Cheers