I have a maxtor 250GB SATA HDD. Its rated at 7200rpm. When i check the temps of the HDD from HW Monitor it shows 38-42C. But when i touch the bottom part of the HDD, (the part where the circuit is) i fell that its very hot. I cant kepp my finger on it for more than 4 or 5 seconds. Its very hot for the finger. So my question is does the HDD require a fan? Or else will the increase in heat reduce the performance of the HDD?
Some older HDD requires a heatsink... the heatsink is your case (the metal that touches it) and that is only if you do crazy HDD intensive task. So not a problem. Today's HDD are cooler during operation and is of no worries no mater how you set it up. Your temps are fine. You were probably touching the processor of the HDD, which gets warm, but not enough to get a heatsink.
The cooler the drive, the longer it lasts for any given operating conditions. Does your case not have a front fan that blows across the drive bays? I always make sure any case I use has this. Your temps aren't terrible, but if they're too hot to touch for more than a few seconds, I'd think about cooling them.
I use an Antec 1200 case and only have one HDD, so I sit that in the middle slot of one of the drive bays, right in front of the 120mm fan, that way I have cool air blowing over and under the harddrive. Never checked the temp but I have constantly had harddrives fail on me so invested in a cooler case and fingers crossed I have had no problem with my drive yet.
I read a report a couple of months ago(sorry don't have the time to look it up) that tested hard drive life within certain temperatures, and it actually showed a statistically significant change in hard drive life from 30c to 40c. And by that I mean that the test showed that the hard drives they used lasted LONGER when they averaged 40c instead of 30c, so take that how you will. I personally have never had a hard drive fail from anything but abuse(spilled a coke on my WD my book ), and I pretty much stick to western digital just because they've never let me down. But yea, 42c isn't cool, but I personally don't think HD's need to be "cool" like other components.