Might not be the WD's fault, here is an old Thinkpad-Mailing List thread where the guy updated the BIOS and his not new Hitachi DK23EA-40B started heating up...
> I have a G40 (2384-33U) with a Hitachi DK23EA-40B hard drive. In the
> last couple of days, my SMART monitoring software, HDDLife, has warned
> me that the hard drive is overheating (over 45 degrees C). The hard
> drive sensor starts at about 31 degrees C on the first reading, and
> gradually increases to about 55 degrees C when the system fan turns on,
> which cools it down just a little.
> Hitachi specifies 55 degrees C as the maximum working temperature, and I
> haven't seen it go above 56 degrees C. The ACPI temperature reported by
> SpeedFan is about 55 degrees C. Hmonitor reports a CPU temperature of 42
> degrees C.
I have investigated this problem further by putting the hard drive in an
external enclosure, and then booting from an Ubuntu Linux Live CD. There
I was able to monitor the motherboard temperature, while reading the
entire hard drive to stress test it. The hard drive stayed cool as a
cucumber. The motherboard temperature kept fluctuating, though. You can
see a graph of it here:http://cus.cam.ac.uk/~mh391/2005/thinkpad/acpi.pdf
The temperature goes up until the fan turns on, when it goes back down
to a decent level. Then the fan turns off and the process repeats. I
suspect that the BIOS update may have increased the threshold for
turning the fan on, either to increase efficiency or decrease volume. I
wish I could just leave the fan on all the time, but there doesn't seem
to be a way to do that. But since the fan seems to be working fine when
it is actually turned on, and it passes the PC Doctor diagnostics tests.
Since a new fan assembly is so expensive here in the UK (more than the
equivalent of USD 100), and I think the chance of damage to the solid
state components is slight at these temperatures, I think I will just
start backing up my data daily rather than buying new parts. I hope it
is just a BIOS issue and that eventually a new BIOS will fix this.
If you think I'm being a total idiot and I really must replace the fan
or get external cooling or something, please don't be shy about letting
... it really should run cool... so I definitely wouldn't blame the WD 1st after reading that.