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Need Help with MC462

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jwells11

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Jun 17, 2001
I want to get a Swiftech MC462 heatsink for my Athlon 1.4ghz. I also want to insert a temp probe. Two options would be to drill laterally into the heatsink base per AMD, or drill vertically all the way through the base to the other side. I gather the second option is more accurate. But there's no way I'm going to sand the surface of a MC462, as smooth as it is. This makes it difficult to get the tip of the probe perfectly even with the face of the heatsink. That is, I won't be able to sand away excess epoxy and probe to bring them flush. It will have to dry perflectly flush. The only way I can think to do this is to place some saran wrap on a piece of glass, place the heatsink on the saran wrap face down, inject the expoxy and place the probe, let it dry, peel off the saran wrap, and hope the expoxy and probe are perfectly flush and that the expoxy didn't spread out past the hole. Do you think this will work? How thick is ASII? Lastly, what type of probe and readout can I get for this type of hole that's under $50? Thanks much in advance.
 

Hoot

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Joined
Feb 13, 2001
Location
Twin Cities
A lot depends upon how accurate you want your readings to be. I drilled both my MC-462As from the pin side through the baseplate. I felt it was less injurious to the performance than a lateral hole all the way across the baseplate. The good news is you don't have to do either. Just buy an Enermax digital thermometer with a strip thermistor and slip it between the CPU and the baseplate, until it butts up against the core. Done properly, there is actually room to spare, so you don't have to worry about it interfering with the mating of the baseplate and the core. You can get a single unit for $14.95 or dual units for $20.00. I started out with a single unit and after I trashed it (don't ask), I bought the dual unit. Now, I can monitor the air going into the HSF and the CPU core temp. It reads within .1C of a type K thermocouple and Fluke 2190A Lab Grade Digital Thermometer. I wrote an article on a slight mod to the strip so that it can reach all the way in to the core. Unmodded, it stops about .5cm short of the core. Not a major mod.

Hoot
 
OP
J

jwells11

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Joined
Jun 17, 2001
Thanks, Hoot. I was looking for that article on the site, and I can't find it...what's the heading? A couple of questions:
1. how much of a reading variance is there compared to the vertical hole method.
2. do you think epoxying the couple to the side of the core with Arctic Circle epoxy might enhance the thermal connection?
3. if you simply abut the probe against the side of the core, it doesn't seem like there's much of a connection, i.e. seems like there needs to be pressure on the probe pushing against the core.

Any thoughts?
 

Hoot

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Joined
Feb 13, 2001
Location
Twin Cities
Is that Arctic Circle grease from Seal or Whale blubber? :D
Sorry, I couldn't help myself. ;D

I'll email you the article. Can you handle a Word 97 document file?

Hoot
 

Hoot

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Joined
Feb 13, 2001
Location
Twin Cities
It just occurred to me that there may be some others interested. Doh!

I calibrated the strip thermistor against my type K thermocouple and Fluke Lab Grade Digital Thermometer. It was within .1C. Not bad for the price.
This is the interesting part. With the strip thermistor butted firmly up against the edge of the core and a small dot of AS Epoxy holding it there, it reads between 1-2C higher than the drilled thermocouple resting upon the top of the core. I sincerely believe the difference is due to the fact that the drilled thermocouple is not only in contact with the core, but also the 3/8 inch copper baseplate on my MC-462A. i believe some of the heat is being wicked away from the thermocouple junction by that contact. In order to better insulate the thermocouple from the baseplate, you would need a bigger hole and put heatshrink tubing around the junction. The bigger the hole, the bigger the negative impact it has upon the HSF performance. The strip thermistor is thin enough so that it does not touch the copper baseplate. I'll open myself up for criticism by saying that IMHO, the strip thermistor reading is more indicative of the temp inside the core than the drilled thermocouple, but, who am I to argue with AMD. Sorry for the long answer.

Hoot
 
OP
J

jwells11

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Jun 17, 2001
Would you get a more accurate temp if you stripped off the yellow covering that surrounds the probe tip, and epoxyed the then-exposed metal to the side of the core? The probes I've seen are usually bare metal. Seems like the yellow covering acts as an insulator.
 

Hoot

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Feb 13, 2001
Location
Twin Cities
That's exactly what I did. I actually trashed the first one as I tried cutting the Capton back a little too far with my dikes. Crunch! The best approach is to snip it back close and then shave the last little bit with a fresh X-acto blade. One fellow finished up with a nail clipper also. I don't have a picture to attach here at work, but essentially, you only need to expose the very end of the tip, not the entire SMD thermistor.

Hoot
 
OP
J

jwells11

Registered
Joined
Jun 17, 2001
Not to belabor the point, but if the the probe comes standard with the yellow jacket, perhap the added thermal resistance caused by it is already imputed into the read out. And perhaps a bare thermistor is giving you too high of a reading.
 

Hoot

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Feb 13, 2001
Location
Twin Cities
Somehow, I don't think they went to that much trouble for a device that sells for $14.95 or 2 for $20.00. ;D

The Capton would eventually reach the same temperature as the core and the tiny thermistor is not much of a sink, so the thermal resistance of Capton is insignificant. No need to compensate for it.

Hoot