Outstanding performance, depending on fan used – Joe
SUMMARY: An excellent choice for aggressive CPU cooling, but noise may be an issue.

The good guys at Thermalright were nice enough to send their latest, the SLK-900-U for a test spin. This is the largest of the SLK series – it measures 99mm x 55mm x 43mm high – without fan – and weighs in at about 570 grams. Due to its size, only 80mm and 70mm fans can be installed if used for P4 cooling with the standard retention bracket.
The SLK-900-U ships with parts for Socket A and P4 mounting:

For P4 use, users have the option of either using the standard retention bracket or removing the bracket and mounting it with spring-loaded bolts; this option requires removing the motherboard form the case. For AMD use, users must remove the motherboard – the SLK-900-U uses the backing plate and spring-loaded bolts. I have not tested it on a motherboard yet but will shortly.
In addition, fans ranging from 70 to 92mm can be mounted on the SLK-900-U, with the exception noted above.
The base is well finished:

When I ran my nail over it, I could not feel or hear any ridges.
I tested the SLK-900-U with Vantec’s Tornado, a Sunon 80 x 38mm fan, model #PMD1208PMB1-A rated at 84.1 cfm @ 5700 RPM, 55.2 dBA, 9.1w; this fan features vanes in the base to straighten airflow off the blades. I also used a 92mm fan, an ADDA model #AD0912UB-A71GL, rated at 60 cfm @ 3300 rpm, 39.4 dBA 4.7w. I varied voltages to get a range of fan speeds and measured rpms using an Omega digital tachometer.
I measured fan noise with a Radio Shack sound meter 8″ from the fan’s intake. These are not comparable to noise levels reported by fan manufacturers; noise is usually measured at three feet from the fan.
The SLK-900-U was tested on the CPU Die Simulator which gives results that are unaffected by motherboard influences.
Heatsink |
Die Temp
|
Ambient Temp
|
Delta
|
C/W
|
SLK-900-U, Vantec 80, 5530 rpm, 74 dBA |
39.2 C
|
24.0 C
|
15.2 C
|
0.22
|
SLK-900-U, Vantec 80, 3995 rpm, 66 dBA |
41.1 C
|
23.6 C
|
17.5 C
|
0.26
|
SLK-900-U, Vantec 80, 3000 rpm, 56 dBA |
43.9 C
|
24.3 C
|
19.6 C
|
0.29
|
SLK-900-U, AADA 92, 3934 rpm, 65 dBA |
42.2 C
|
23.8 C
|
18.4 C
|
0.27
|
SLK-900-U, AADA 92, 3244 rpm, 56 dBA |
45.5 C
|
24.8 C
|
20.7 C
|
0.29
|
C/W = Delta / CPU Watts