I bought a new 500GB Seagate drive, put it in the USB box and it's working just fine. I copied around one hundred gig of stuff to the box and had no issues with heat, error messages or slowness.

Two drives with the same rotational speed and the same number of platters are likely to have similar heat output if they're both spinning for the same period of time, but modern 3.5-inch drives can actually differ quite a lot in platter size. Straight high-capacity consumer drives will all probably have platters about as big as can be crammed into the casing, but higher-performance, lower-capacity drives - especially the 10,000RPM type - will commonly have platters that're smaller. That's mainly because a physically smaller platter means the head assembly doesn't have as far to go, which reduces seek time. Smaller platters mean less air friction, all other things being equal (which of course they aren't, if a big-platter drive is 7200RPM and a smaller-platter drive is 10,000RPM).

Apart from that, I think the only things that significantly affect heat output are the power levels of the head voice coil and of the spindle motor, which for consumer drives are pretty similar across the board.

Your two drives are presumably both straightforward consumer units with full-sized platters. They probably have the same number of platters, too - just one in each drive - though you'd have to check the model numbers to be sure. So if one of them runs a lot hotter than the other then yes, it is indeed possible that there's something wrong with it, like a voltage regulator that's dumping a lot more watts than it should or a gummed-up bearing that makes the motor work a lot harder.

I doubt the Astone is the cause of my overheating issues. I mentioned it because I believe the drive it's self is to blame. Overheating, slowness and error reports are of coarse common symptoms of a faulty drive. The fact that this drive is new (fresh out of it's shrink wrap) made me doubt it was the cause. The drive is an RMA replacement...

Seeing as my old 80GB drive in a USB box barely gets warm and it has no fans, not even a single vent, I reckon I can safely blame the drive, not the Astone.

Which brings me to wonder, would an 80GB Seagate drive produce significantly less heat than a 320GB Western Digital drive?

It's quite possible that a box like this will overheat if used for hours constantly when the ambient temperature is high. But so will a bunch of other fan-cooled boxes, when their little fifty-cent fans pack it in after about two months. If you want really good cooling, you need a drive box like a small PC case, with proper long-lived PC fans to move air through it. There are several more or less expensive off-the-shelf options here, but you can of course also pretty easily just use an old PC case for this job.

I have managed to get the Astone to create some interesting errors all my own, though. I'll post again when I get them clearly codified :-).

Event Type: Warning
Event Source: Disk
Event Category: None
Event ID: 51

Description:
An error was detected on device \Device\Harddisk1\D during a paging operation.

I had no problems copying 160GB of data. After that I tried copying 60GB from another USB drive on the same system. Around 30 minutes later firefox stopped responding then I saw the above error in Event Viewer 50 times. I reckon the drive it's self is causing my issue.

I tested (unintended test, but anyways..) by formatting the Astone USB box equipped with a 320(298)GB hard disk then moved all the data from my old 80GB USB hard drive (around 60GB) to the Astone.

The Astone took nearly two hours to fully format the drive. Maybe the drive has issues even though it's new, I took it out of it's anti-static shrink wrap today and installed it into the Astone.

To give a very rough idea how hot the Astone got; I could smell it (the 'new gear' smell) when entering the room and when I sat at my desk the smell was very strong.

I have a couple of external drives that spin down when they lose USB power. I am now looking for an *unpowered* USB hub to dedicate to my external drives!

Hey Dan, any chance you can do a Plasma vs LCD TV write-up? What I would like to know is how much truth there is to "Plasma uses more power and has a shorter life-span than LCD".