I wonder how they longevity of the fans work.
I've tried two disk cooler models ($10 ea) that were
types of fans that screwed onto the drive (15K SCSI). One used 2 tiny fans, maybe 2x50mm? -- the other a fan as wide as the HD -- about 70mm. They were by the same company, vantec, and the larger fan had about 80% more airflow at lower RPM's. Rated dB's were about the same. They both brought down the drive between 15C-20C (from +50C -> low 30's (as low as 30C). They both were made from Aluminum. I liked the double-fan model better, on aesthetics -- and it had a lower profile, but after 6 months, the fans wore out! -- I'd open her up and see the fans barely turning. So I'm hoping the larger fan at a lower RPM will have a longer life -- it also might be I got a bum unit. But for $10 ea, they're worth a try. I had a drive cooler that installed in the entire 5" drive space and it also had a real tiny fan -- (fitting vertically in the drive case) -- but the little fan was the first thing to stop working. So I'm a bit leary about those little fans.
I'm looking for some remote monitoring solutions, -- something to allow me to place probes in the computer and can be read by software -- at least the computer would know when there was a problem. As it is now, it's such an old computer, it just hangs when it gets too hot and on bootup, you might see a thermal failure if it was a cpu fan that stopped....bear skins and stone knives (440BX motherboard, circa 1999)