Thermalright SK6+

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Solid performer – Joe

SUMMARY: Another solid performer from Thermalright.

SK6+

The kind folks at Thermalright were nice enough to send a sample of their latest heatsink, the SK6+. This is similar to the SK6 but heavier – the SK6+ weighs in at about 400 grams while the SK6 is 330 grams – more copper for better cooling performance.

The base is well finished:

Base

When I ran my nail over it, I could barely hear, but not feel, the polishing marks. The clip engages all three heatsink lugs although it requires a screwdriver to mount. The SK6+ ships with two sets of clips to mount 25 mm and 38 mm fans, as well as a tube of thermal grease:

Parts

In summary, a copper heatsink with a secure clip (screwdriver needed).

THE TEST

The SK6+ was first tested on the CPU Die Simulator which gives results that are unaffected by motherboard influences. I then tested it on a Shuttle AK31, modified to read AMD’s on-die diode, as an example of what users might see on their systems.

The fan I used was a Delta 60, Model #FFB0612SHE – a 60 x 38mm unit rated at 43 cfm @ 7000 rpm, 50 dBA. I varied voltages to develop a range of rpms and C/Ws so readers can evaluate performance with different fans. I measured noise at various rpm settings, as noted below:

TEST RESULTS – CPU Simulator

Heatsink
Die Temp
Ambient Temp
Delta
C/W
SK6+, 7122 rpm, 50 dBA
41.0 C
22.2 C
18.8 C
0.28
SK6+, 5992 rpm, 47 dBA
42.1 C
22.6 C
19.5 C
0.29
SK6+, 5000 rpm, 43 dBA
43.9 C
22.9 C
21.0 C
0.31
SK6+, 4012 rpm, 39 dBA
45.7 C
22.7 C
23.0 C
0.34

TEST RESULTS – Motherboard
CPU/Motherboard

CPU Die Temp

Ambient Temp

Delta

C/W

CPU Back Temp

XP @ 1467, Shuttle AK31

42.5 C

23.9 C

18.6

0.29

33¹ C

¹In-socket thermistor per MBM

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

Interpreting C/W: For every watt (CPUw) that the CPU
consumes, the HSF will limit the CPU’s temperature rise to (C/W x CPUw)
plus the temperature at the HSF’s fan inlet. For example, at an ambient temp of 25 C, a C/W of 0.25 with a CPU radiating 50 watts means that CPU temp will increase 50 x 0.25 = 12.5 C over ambient temp, or 37.5 C. The lower the C/W, the better.

Die Simulator results place the SK6+, with the ultra-noisy Delta 60, in the top rank of heatsinks (Heatsink Ranking). Less noisy settings lower performance a bit (as expected), but still very credible cooling.

The difference between a screaming 7000+ rpm and a tolerable 4000 rpm is 6 C. Users might consider using a rheostat or a temperature controlled fan to moderate noise as requirements dictate.

CONCLUSIONS

Thermalright’s updated SK6+ is a very competitive entry. Performance scales nicely with rpms, so tradeoffs between performance and noise are predictable.

Thanks again to Thermalright for sending this our way.

Email Joe

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