Solid performer – Joe
SUMMARY: Another solid performer from Thermalright.
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:
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:
In summary, a copper heatsink with a secure clip (screwdriver needed).
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:
| 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 |
| 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
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.
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.
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