Card Cooler Thin Fin Heatsink

UPDATE 11/16/99: Thin Fin vs. Vantec – Who’s King Of The Hill?

SUMMARY: The Card Cooler Thin Fin is the best “Intel Approved” heatsink around – incredible as it has only one fan. Hopefully we will see more performance increases as folded fin designs become more prominent.

When I first tested the Vantec P3D 5030, I called it the best PIII heatsink that meets Intel’s Standards (Vantec P3D 5030 Review)
; the Alpha PIII is the best air-cooled heatsink even if Intel doesn’t like its weight. I recently tested Card Cooler’s Thin Fin PIII heatsink (see below) and was impressed. At the time I felt it was the best but did not have a Vantec P3D 5030 to test it against, so I bought one – the results are very interesting and conclusive.

To test these out I used my naked PII 300 SL2W8 running at 450, 2.0 volts. This produces 33 watts, slightly less than a PIII 600 at spec (34.5 watts). The naked PIIs have the same hole pattern as the PIIIs (obviously they use the same PCB) so mounting the heatsinks presented almost no problem. The single problem area is back plate mounting; what I did was to use short lengths of small neoprene tubing which fits over the mounting pins and serves to snug up the mounting plate to the heatsink. You can find this tubing is any hobby store – it’s used to carry fuel for model plane engines.


The setup was simple – record CPU temps running Prime 95 using the thermal diode on the PII 300, record fan intake temps and compute system c/w. The results:

Thin Fin: C/W = 0.52
Vantec: C/W = 0.58

This translates into an observed temperature difference between the two of 3 C – the Thin Fin stabilized at 34 C and the Vantec at 37 C. This is enough of a difference to make it a significant one and to call the Thin Fin the best Intel approved PIII heatsink. What is remarkable is accomplishing this with a single fan (very quiet compared to two fan versions) – it attests to the remarkable efficiency of folded fin heatsinks compared to extrusions. Hopefully we will see more folded fin heatsinks in the marketplace – the performance bar is raised once again.

Original Review


An outstanding P3 CPU Cooler – Probably the best single fan P3 cooler on the market.


The Card Cooler sent me a very interesting heatsink to evaluate, one made of aluminum “Thin Fin” construction; this is a bonded-fin heatsink. The difference between this one and the usual heatsinks you see is that most heatsinks are extrusions – they are made by forcing aluminum through a die. What comes out is then chopped up into small pieces and finished into individual products – very easy to make, cheap and does the job.

Bonded fin heatsinks are constructed differently; the fins are bonded to the body of the heatsink, could be by tack welding, epoxy or just punching it onto place. This one looks like it is mechanically bonded – a punch dimples the top and bottom of the fins into the shroud cover (pix/specs here). In the heatsink universe, bonded fin heatsinks are better performers than extrusions but more difficult to build, all things being equal (are they ever?).

What makes these so different is the thickness of the fins; in extrusions, the fins are usually 1/16″ thick – there is a limit to how fine you can extrude. The “Thin Fin” uses aluminum stock that is not much thicker than an index card. This construction enables the “Thin Fin” to squeeze in 18 fins that are roughly ¾” x 4 ¼” long. This amounts to a cooling surface area (fins only) of about 115 square inches (0.8 square feet). A Global Win FAB 28, a very good extruded heatsink, has 21 fins (1/16 inch thick) that measure about 5/8 x 1 7/8 inches. This is about 50 square inches (0.35 square feet), so the “Thin Fin” packs 2.3 times more surface area into roughly the same footprint.

The “so what” of all of this is that the “Thin Fin” is one helluva cooler considering it has only one fan. I calculated the C/W of the “Thin Fin” at 0.68 and the FAB 28 (two fans) at 0.70 – great performance considering it has about ½ the “horsepower”. With two fans, the “Thin Fin” would probably rank pretty high. I experimented a bit by mounting a single YS Tech on it, building a shroud made out of tape to funnel the airflow into the heatsink. With the YS Tech, the “Thin Fin” cooled my test peltier to 15.8 F compared to 18.7 F unmodified, so increased air flow will result in better performance.

I ran some other coolers on the peltier test rig under the same conditions, and the “Thin Fin’s” 18.7 F compares to 9.5 F for an Alpha Socket 7, 20.8 F for the Global Win P3 AOS 20 (two fans) and 23.2 for the Vantec P3 5020R (one fan).


The “Thin Fin” is a great heatsink for those who don’t like noisy cooling solutions. At less than 30 dBA, this is one quiet cooler. Its performance is perfectly adequate for any PIII or naked PII and, although not up to Alpha standards, it out-performs a number of P3 heatsinks. I will use this when building systems to go into office environments where PC noise is a factor.

As a side note, Motherboard Monitor reports the fan speed at 10,000 rpm which is over the spec for the fan (Sunon KD 1205PFB1-8). This might explain its great performance although I can’t tell you how many cfm this produces.

One other note – I measured the temp of my PII 300’s cache chips, and with the CPU running at 31 C (thermal diode, 300 MHz), the cache chips were 25.8 C. At 450 MHz, the CPU temp was 36 C with the cache chips at 27.8 C. Note that the “Thin Fin” has slots in the bottom to cool cache chips, a worthwhile feature for P3s and naked PIIs.

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