Email from Gabe at Swiftech:
“You know that I am always in search for added performance, so when EBM (Pabst) notified me that they were discontinuing my NGHH (rated at 33cfm), I immediately contacted the Delta people. I received a sample of their AFB0612EH, their most powerful 60mm rated at 38CFM fan on Friday, and proceeded to compare performance. The first thing I immediately noticed is how unbearably loud the Delta is. (under)Rated at 46.5dba, one Delta is actually louder than 2 EBM’s running together: each EBM is 43dba, so 2 running together is 43+3= 46dba.
Well I thought, if this thing performs as good as it screams, maybe my customers will forgive the added noise.
Once you read the test results below, you will understand how hugely disappointed I was.
In theory, 38 cfm compared to 33 cfm represents a 15% increase in performance. In practice however, it only translates into an average 2.5 % improvement. I do not believe that this is a case of diminishing returns. The design of the Delta is simply not as good compared to EBM’s, and the added unconvenience of the noise is clearly not worth the marginal improvement this fan can provide.
Conclusion: is Swiftech out of their wonderful 33cfm EBM (Pabst) fan?
Nope. It turns out that EBM makes an NHH fan, which is a ball bearing instead of the NGHH sleeve bearing. It has improved resistence to thermal constraints (10C better), with the same flow characterisitcs. We’ll still be breathing hard and (relatively) quiet for the foreseable future :-)”
SUMMARY 9/12/00: Alpha is the only heatsink I have found so far that delivers good air cooling for AMD’s Duron and T-Birds.
I’ve been testing a number of air-cooled heatsinks on my overclocked Duron 650 @ 935 and T-Bird 750 @ 100, both at 1.85 volts. Up till now, I have not been real pleased with anything I used – temps are around 55C/131F and sometimes climbing. Not good.
I finally received an Alpha PAL 6035 from PC NUT that I ordered a while ago; Alpha is backordered like crazy and getting these are not easy. If you are not familiar with the PAL6035, if it is like the old socket 370 PFH6035 except it has a copper base and more fins. Overall, a nice improvement on the original design.
As soon as I received it, I put it on my T-Bird (1100 @ 1.85v). Of all the Duron/T-Bird certified mounting clips, Alpha’s was the easiest to clip on the socket, although I still had to use a needle-nosed pliers to do it. Installing it in a case will be tricky. I ran it (ambient 23.4C/74F) with the following results:
Prime 95: 53C/127F
Frankly, not thrilled with these results. It held steady as Prime 95 chugged away – at least that was a plus. The fan I put on was a YS Tech rated at 26 cfm; I remembered I had a heatsink from Swiftech that used a Pabst fan rated at 33 or 36 cfm. I scrounged around, found the Pabst and ran it on the Alpha:
Prime 95: 49C/120F
More like it, although still too warm for my tastes. Interesting to see how more cfms deliver better peformance; it suggest that the Alpha has “headroom” and even more aggressive cooling (maybe a 120mm running a duct to the Alpha?) might knock temps into the mid 40s.
However, this is the FIRST air-cooled heatsink I have found that keeps the T-Bird under 50C/122F. The problem is getting a fan like a Pabst to mate with it – maybe someone knows a distributor who will supply these.
If you have to go air-cooled, the Alpha PAL6035 is one that will at least keep you on the low end of the temp curve.