Review: Thermalright SP94, SP97 & other heavyweights

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Dec 22, 2003 by Mike Chin

Products & approx. market prices in US$

Thermalright SP94 P4 Heatsink $50
Thermalright SLK900U on P4/socket A $40
Thermalright SP97 socket-A heatsink $50
Zalman ZM7000A CU/AlCu on P4/socket A $35~50


Sharka Corp
Silicon Valley Compucycle (SVC)

Thermalright has held a lofty position at the top of the heatsink ranks here among silence seekers. They are also regarded as tops by legions of overclockers, gamers and performance enthusiasts elsewhere. They provide cooling performance second to none when you're using a banshee fan approaching 100 CFM yet do amazingly well even when you are babying your hearing with a gently undervolted Panaflo.

Thermalright's ascendance goes back at least to their SLK800, introduced over 18 months ago. The SLK900 picked up and continued where the SLK800 left. But earlier this year, the ZM7000 flower-turned-radial Zalman heatsink stepped into the fray, and since then the race has been very close.

The SP94 is Thermalright's latest heavy metal flagship for the P4, introduced a few short months ago. It incorporates three heatpipes in an all-copper structure that is a natural evolution of their previous products. The just-introduced SP97 is Thermalright's socket-A version of the SP94. These heatsinks represent the best Thermalright has to offer at this in time. The progress is more evolutionary than revolutionary -- at a quick glance, they look much like the SLK900 with a bit of additional plumbing. (However, close examination shows other differences; more on this later.)

The other heatsinks are listed at the top of the page because even though this review is ostensibly about the SP97 and SP94, the other heatsinks were needed as reference points for comparison. Furthermore, the SLK900U had not been tested with an AMD CPU before, and neither had either of the Zalman ZM7000s, which in the most recent A version, can be used with socket-A. These heatsinks, already reviewed in P4 applications, get coverage here in the context of socket-A CPU cooling. On top of all this, a change was made to the P4 test platform: The P4-1.8 was retired (too cool) and a much hotter P4-2.8 introduced. Finally, my socket-A platform was upgraded from the now ancient KT-133A to a much more recent Asus and a XP2500+ with Barton core.

As you might guess, this is going to be a wild and wholly heatsink roundup. With the profusion of models that work with both P4 and Socket-A, it's hard to keep it all neat and tidy. And we have not even touched the Athlon 64 yet! So hang on to your... er, fans?... and bear with me please.

SP94 & 97 Specifications

All copper design for maximum performance
Soldered fins to base to ensure effective contact
92mm stock fan for more cooling capability
Screws through motherboard mounting for LAN party

L99 x W59 x H45 (mm) Top, without fan
L67 x W81 x H45 (mm) Bottom, without fan
590 grams (heatsink only)

L99 x W59 x H50 (mm) Top, without fan
L75 x W55 x H50 (mm) Bottom, without fan
585 grams (heatsink only)


As the top photo shows, the SP94 and SP97 look very similar. In terms of their main fins structure, they are virtually identical in size to the SLK900. There are a few key differences between the SP94 and SP97, mostly related to the requirements of the difference CPU form factors they are meant for.

The first of these is the base and mounting structure. The SP94, on the right in the photo above, has 4 hefty square nubs that extend out of the corners of base. Each of these has a hole in it. These are the mounting holes. They line up with the holes around the CPU socket in any P4 motherboard -- once the usual plastic heatsink retention bracket is removed.

The SP97, on the left above, also has 4 lugs with holes in them, but the lugs are not quite as hefty, and they line up with the 4 HS mounting holes that can be found on some AMD socket-A motherboards. These through-the-board HS mounting holes are not nearly as common as they used to be. Some months ago, AMD announced the cessation of official support for this HS mounting scheme. (I don't believe this was ever a requirement for AMD socket-A boards. It is hard to imagine the benefit of removing the recommendation or guideline, however. It certainly makes life harder for performance HS companies that have relied on these mounting holes -- which undoubtedly allow the secure use of far heavier heatsinks, especially in transit. One imagines some backroom politicking behinds the scenes at AMD.)

Two other minor differences exist:

  • The SP94 base is very slightly thinner (though bigger in area than the SP97 base), making the SP97 slightly taller.
  • The SP94 has one more fin than the SP97.

One significant design departure for the SP94/97 is that the base structure is flat, and the fins are bonded directly to the base. The SLK800 and 900 both utilize a heavy triangular-cross section tunnel running the length of the heatsink. This is visible in photos in the SLK900 review as well as the SLK800 photo below.

SLK800's triangular-cross section "tunnel": This design feature is not used in the SP94/97.

The photo below show the three heatpipes, fine fins and a base that's flat on both sides. One might conjecture that the triangular-cross section tunnel, being a part of the base and connected quite high up on the fins, has an effect similar to the heatpipes.

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