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Thermalright SLK-900A Heatsink Review

Thermalright is a well known brand for overclockers. When they launched the SLK-800a last year, it was called, from many, the best air cooling solution out there, it outperformed in many reviews the Swiftech MCX-462U, and it didnt need the 4 motherboard standoff holes, that many motherboards didn't have and still don't. The SLK-800a also improvised by using a smaller base, so that capacitors would not be in the way. The SLK-900A, is Themalright's answer to people who do not have motherboard heatsink mounts. The SLK-900U has been around for some time, allowing users to use higher CFM 92mm fans, which also offer lower pitch. A larger surface area, and base, where heat is dissipated has also been improved. We will see if it meets the demands that the SLK-800a accomplished. Let's begin with the heatsink packaging:

The SLK-900A cardboard box

The heatsink is protected well, along with the box, packing peanuts were used to protect the box, the SLK-900a was intact when I received it

        This package comes with everything that the SLK-800a had, except this time they included themal compound, this one cant be compared to Nanotherm's or Artic Silver thermal compounds, but  it's a lot better than using a TIM, a thermal pad. The package also comes with 4 CPU pads to avoid pressure to the core, since the base of this heatsink doesn't come in contact with the AMD CPU pads, it's highly recommended that you install them in the base of this heatsink, since you probably don't want the core to chip. Clips are also included for 70mm TMD, 80mm, and 92mm fans.

The SLK-900a package

The 4 heatsink pads

The Thermal compound, having similar characteristics to the Shin Etsu compound

The base is well protected against scratches

    The manufacturer's specs (from Thermalright.com):

     Thermalright also has a very good drawing of the dimensions of the heatsink (taken from thermalright.com):

    The picture above will tell you which clip holes to use for each fan. This heatsink might not fit in all motherboards, but it gives you a very good idea how big the heatsink is.

         Comparing to the SLK-800a dimensions:

L87 x W56.4 x H48 (mm) - Top, without fan
L57.5 x W56.4 x H48 (mm) - Bottom
L25 x W56.4 - Base

Weight: 505g (heat sink only)

       The SLK-900-A is not that much larger, we will see if it performs better. To compare both heatsinks, and see if there is increased surface area, we will be using the same fan, a Coolermaster variable fan. We will be also using the Coolermaster ATC-220, with the side panel closed.

 Like the SLK-800a, the SLK-900a looks almost identical. The base is a lot smaller, but as you come higher, it's elongated. This allows capacitors and transistors from being in the way, if the base was as long as the top of the heatsink, it would fit in very few motherboards.

  A front picture of the heatsink

       This heatsink comes with steppings, to accommodate 70mm, 80mm and 92mm fans.

Top-side view of the heatsink

      If you take another look at the side of the heatsink, you can see the curved design to accommodate most motherboards. You can also see how all the micro-fins are connected together in what looks like a fan shroud.

A side view of the heatsink

      The SLK900a, like the SLK800a predecessor, comes with the uniquely shaped base, which comes with contact with the fins not just from the base, but in the center of the HSF, which allows heat to dissipate from the base to the fins faster. The 37 micro fins, each with a massive surface area also allow heat to dissipate faster.

A top view of the heatsink, where you can see the micro fins come in contact with the "vertical side" of the base

       This heatsink weighs 527 g. Though it's a minimal difference to the SLK-800a, the triple lug design will keep the heatsink secure. Thermalright has had the SLK-900U for along time, with the 4 motherboard standoffs which allow a more secure fit to the motherboard, stronger than any socket clip design.

Any 92mm fan will fit, whether it's 25mm or 38mm in thickness

A triple clip keeps this heavy heatsink secured

         The heatsink offers a wider base, as you can see below, and is also longer to accommodate 92mm fans. It is only 3mm wider though, from 56mm (SLK-800a) to 59mm (SLK-900a). That is a disadvantage of this heatsink, that some airflow is lost to the side, the heatsink would have to be 92mm wide in order to be 100 percent efficient to the fan, but the triple clip is on the way.

Base comparison between a SLK-800a (left) and a SLK-900a (right)

Size comparison between SLK-900a (foreground) and SLK-800a (background)

Length comparison between the SLK-800a (left) and SLK-900a (right)

      The pre-lapping is well done, and you probably wont have to lap it, most likely since there would be no temperature drop.

Coin on top of the SLK-900 base

          Like the SLK-800a, the SLK-900a does not come in contact to the AMD CPU pads that are placed in the edges of the processor. It is well recommended that you use these, to prevent the chipping of the cpu die, since this is one heavy heatsink.

The CPU pads to relieve pressure on the AMD die

Test system:

-AMD Athlon XP 2500+ Barton core

-Soltek 75FRN-L nforce2 motherboard

-Kingston Hyper-x PC3000 256 Mb memory module

-ATI Radeon 9500 Non Pro 128mb

-40 Gb Western Digital 7200rpm HDD.

-Fortron 350 Watt PSU.

-Coolermaster ATC-220 case

The AMD Athlon XP 2500+ Barton in the ZIFF socket

The heatsink installed, not a tight fit

This is the fan that will be used to test the SLK-900a

      Now on to the temperature results. I will be comparing this heatsink to the SLK-800a, since the SLK-800 heatsink is the standard for overclockers, that will be all to prove the performance of the SLK-900a. Both heatsinks will be tested for fairness of results with the same fan, the Coolermaster variable fan at a tolerable 3300 rpms, pushing ~35 CFMs. The CPU will be tested at stock settings (166x11) @ 2500+, and overclocked (11x200) @ 3200+.

The first temperature test will be with the CPU voltage at 1.65v, room temperature was kept ~ 24 C.

The second Test will be with the CPU @ 2.2 GHz and 1.775v

These results speak for themselves. An already excellent SLK-800a, outperformed by 1-3 C. Small as the difference may seem, these are great results. Let me remind you, that the nforce2 motherboard we have reports higher than usual temperatures, these results are to compare the SLK-900a and the SLK-800a, because they have the same test conditions.

Conclusion:

Overall, we achieved competitive results. 1-3 C. difference is nothing to laugh at, since the SLK-800a was reigned the king of air cooling.  With a retail price of 50 dollars, many retailers will sell it for less. The price tag might keep some away, since it's almost twice as expensive as the SLK-800a, but overclockers that want to make every degree count, this is well worth it. At  Overall, this heatsink deserves a:  9.5/10

Pros:

-Excellent Performance

-Ability to use 70, 80 and 92mm fans

-Solid Triple clip design

-Fits in most motherboards

-Superior Surface Area

Cons:

-Somewhat Expensive

-Heavy Heatsink (527g)

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