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Thermalright SLK-948U: We take a look at Thermalright's newest high-end cooler which is similar to their past heatsinks, except now it's universal.

Date: April 29, 2004
Provided By:
Written By: Quasar

Right now, the enthusiast choices for CPUs are either the Athlon 64 or the Intel Prescott. However, a large number of users still use the Athlon XP or one of the pre-Prescott Pentium 4 CPUs. For enthusiasts, top-notch cooling is essential, but at the same time, nobody wants to keep buying a new heatsink with every PC switch, especially if the heatsink they own already costs over $40.

Thanks to (and VL), we got a chance to test the Thermalright SLK-948U. Like previous Thermalright coolers, the SLK-948U shares many of the same design decisions, but this time the heatsink is universal.

The heatsink ships in Thermalright's standard brown box. There are a number of fan wire clips, installation tools (covers AMD XP/A64, and Intel Socket-478), thermal paste, AMD retention bracket, and an installation guide.


Fan DEFAULT - NO FAN. Heatsink is compatible with following fan sizes: 80x38mm, 92x38mm, 80x25mm, 92x25mm, 70x25mm, 70x15mm.
Heatsink Dimensions L95 x W64 x H45 (mm) Fin only, without fan
L67 x W32 (mm) heat sink base
L89 x W38 (P4 mounting frame)
L101 x W38 (K8 adapter installed on P4 mounting frame)
Compatibility Compatible with AMD Socket A/462 (XP, Duron, Thunderbird), and Intel Pentium 4 Socket 478 processors.
Material Copper
Weight 635g

The SLK-948U is a 100% copper design. As most enthusiasts already know, copper is typically the preferred material (as opposed to aluminum) in performance coolers. Copper can absorb heat much faster than aluminum, but retains heat longer. For overclockers, I can see where copper's heat absorption can be handy when an overclocked CPU initially powers on. The heat created may be too much for aluminum coolers, but it may be handled by copper ones.

The SLK-948U rings in at 635g, which is over 100g heavier than some of their past coolers. Thermalright didn't get cheap when pouring the copper into its mold. By default, the heatsink doesn't ship with any fans, but it can accomadate 70mm, 80mm and 92mm fans.

Unlike many heatsinks, the SLK-948U is not a "square" design, but rather, it is tapered going up. This will allow the heatsink to fit in most motherboards that follow the manufacturer's clearance specifications.

The edges of the heatsink are staggered to accomadate the different sized fans. Rather than using push pins, or traditional screws for installation, they use metal wire clips to secure the fan.

Depending on the size of the fan, you install the wire retention mechanism into one of three holes (on both sides of the heatsink, on either edge). The corners of the hooks then go into the fan holes themselves.

Pentium 4 installation is as simple as adding a couple clips. There are actually two methods for P4 installation (the second is a bolt through method), so your application options are flexible. Athlon 64 installation is more involving, as it requires motherboard removal, but no more complicated than removing the default AMD retention bracket and using the one Thermalright includes.

Test Setup - Pentium 4 3360MHz

ASUS P4C800-E: Pentium 4 2.8B (21x160) @ 1.8v, 2 x 256MB Kingston HyperX PC3500 (2.5-3-3-6), HIS Radeon 9600 XT, 120GB Western Digital SE 8MB Cache, Windows XP SP1, ATI Catalyst 4.5.

Going up against the Thermalright SLK-948U will be the MCX478-V. Both coolers will be outfitted with an Enermax 92x25mm Adjustable Fan (running at 41cfm), as well as a Vantec Tornado 92x38 119cfm fan. Arctic Silver 5 is the thermal compound used for both coolers.

To load up the system, we run Prime95 run for 20 minutes, with Folding @ Home running in the background. Ambient room temperature is maintained at ~23°C/74°F. Temperatures were gathered using Motherboard Monitor.

Enermax Fan (41cfm, 26dBA)

Coolers @ Full Load
Temp (°C)
Thermalright SLK-948U
Swiftech MCX478-V

The Enermax is a relatively low speed fan, but it is far from being what I would consider silent. However, it makes a whole lot less noise than the Tornado, but also move less air. Although the temperatures sit in the low fifties, the P4 is far from being in the danger zone. The SLK-948U has a 0.5°C edge over the MCX478-V.

Vantec Tornado (119cfm, 56dBA)

Coolers @ Full Load
Temp (°C)
Thermalright SLK-948U
Swiftech MCX478-V

With the more powerful (and louder) Tornado, both heatsinks shave about 4°C off the Enermax performance numbers. The fan is quite deafening, but that's the trade-off for better performance. The SLK-948U's performance is 1°C better than the MCX-478-V with the bigger fan.

Final Words

As we've seen here today, the SLK-948U's performance is quite good. Being a universal heatsink, you can easily move it from platform to platform should you need to. Depending if you're interested in setting up a low-noise system, or a loud, overclocked one, you're well covered with the number of fan options allowed.

On the negative, I suppose the future isn't clear as to where AMD and Intel will move in the next six to twelve months, so the future-proofing of the heatsink is unknown. However, for past, present, and the immediate future, this heatsink should have you covered. Installation is quite easy, although it can be a bit more complicated with the Athlon 64. The instructions are quite clear though, so that should not be much cause for concern.

Our overclocked 2.8E is quite a scorcher, and the SLK-948U kept it within tolerable temperatures. There has been some discussion in the VL forums about how it stacks up against water cooling. As I've already mentioned there, the SLK-948U with the Tornado fan does stack up well against water cooling, though we're still going to lean towards a quality water setup at this time. Based on the result's of VL's Koolance EXOS review, we can see there is still a 4-5°C difference between the SLK-948U and the EXOS at the low fan speed setting.

At without the fan, it isn't cheap, but like all critical system parts, you get what you pay for. To save you a bit of coin, up until midnight tonight (April 30, 2004). You can use this coupon when ordering online, enter the code CPCVL043004 during check-out.

Pros: Good performance, excellent quality, universal.

Cons: Expensive.

Bottom Line: Another solid offering from Thermalright. With the current batch of CPUs running hotter than ever, especially in the case of the Intel Prescott, I would put this on my short list for air coolers for that CPU.

If you have any comments, be sure to hit us up in our forums.


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