AMD Retail Heatsink

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Makes a great paperweight – do not use for serious cooling. — Joe

SUMMARY: Makes a great paperweight.

We recently purchased a boxed, retail AMD CPU which is packaged with a heatsink. Not having tested one of these, I thought it would be interesting to see what AMD thinks is adequate cooling.

AMD

The heatsink is an aluminum extrusion with nothing extraordinary about it – smooth fins, etc. It has a fair amount of space between the fins to enhance airflow through them.

The fan is a 60 x 10 mm unit made by
BiSonic. It’s rated at 4700 rpm, 23 cfm. I measured it’s sound at 57 dBA, 8″ from the fan’s intake, with a Radio Shack Sound Meter. This is quiet – the YS Tech 26 cfm unit comes in at about 61-2 dBA.

Fan

Specs: 4700 rpm, 37 dBA, 2.5 watts.

The clip rides on a half circle over the CPU’s center; it is also indexed, as shown by the picture insert. This enables consistent mounting every time. You need a screwdriver to mount it on the socket.

Clip

All told, AMD’s retail heatsink is about what you would expect – adequate cooling at the lowest possible cost. Let’s see what “adequate” means:

THE TEST

I prepared AMD’s retail heatsink by boring a hole completely through the base so I could epoxy a thermocouple above the CPU. The thermocouple is attached to an Omega HH23 Digital Thermometer. Ambient temps were measured with a thermocouple placed about 1 inch from the fan’s intake. I used Prime 95 to stress the CPU on an Iwill KK266+. Arctic Silver grease was used in all tests. CPU Case Temp is the temp at that point where the CPU contacts the heatsink.

Just to see what would happen, I also tested it using a Delta 38 fan.

TEST RESULTS
CPU/Motherboard

CPU Case Temp

Ambient Temp

Delta

C/W

MBM Temp

Iwill KK266+, T-Bird 1400 (72 watts)

50.6 C

23.6 C

27.0

0.38

41 C

Delta 38, Iwill KK266+, T-Bird 1400 (72 watts)

45.7 C

22.7 C

23.0

0.32

35 C

Delta = CPU temp – Ambient Temp
C/W = Delta / CPU Watts

Interpreting C/W: For every watt the CPU radiates, the heatsink will cool the core by the (C/W x watts) plus ambient temp. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that the CPU temp will be 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

Not a pretty picture at all! Even with a Delta 38, it does not get into what we consider “acceptable” – a C/W of 0.30 or less.

Now, figuring that AMD is including this heatsink for some productive use, I tested it as a paperweight.

THE TEST

I aimed a housefan at a pile of papers with the AMD Retail Heatsink on top of them. The housefan was running at full blast, as shown below:

Paperweight

TEST RESULTS

After 5 minutes of flapping papers, the papers stayed put.

CONCLUSION

AMD’s Retail Heatsink may be OK for your mother’s PC, but for serious cooling, it’s not even close. If you buy a retail CPU, figure it comes with a nice paperweight.

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