A tale of two Black Caviar WD5002AALX 500GB drives

It wasn’t the best of times or the worst of times, but I have two Black Caviar 500GB drives which are slightly different and I wonder if anyone here knows why.  Both drives are WD5002AALX made in Thailand, but one is significantly heavier and has four large (maybe three cm in diameter) black plastic caps embedded in the front, while the other is as light as my slightly older Caviar SE-16 320GB drive and does not have the black caps.  The former was made in July 2011, while the latter was made in August 2011.  Both labels state that the cache is 32MB.  Was this simply a manufacturing change or is there a juicy story behind the difference?

Show us photos of the labels and the PCBs.

What are the 2060-xxxxxx and 2061-xxxxxx numbers on the PCB?

What do you get when you run the serial numbers through WD’s online warranty checker?

http://websupport.wdc.com/warranty/warrantycheck.asp?custtype=end

Could we see HD Tune read benchmark graphs for each drive? This will tell us their actual RPM.

Could you also run a short stroked version of the same benchmark, say 3GB and 1GB? This may tell us how many heads your drive has.

How to determine number of heads using HD Tune:
http://malthus.zapto.org/viewtopic.php?t=650&p=2591

The moderator will delete any photos / images containing serial numbers, so I will not post them.

Running the serial numbers through WDC warranty was interesting.  All three drives (I have three, actually) were manufactured in July or August 2011, yet the warranty expires in September 2014 for the two heavy ones and September 2016 for the light one.  So much for the 5-year limited warranty.

Both heavy drives have a model number of WD5002AALX-32Z3A0, while the light drive is WD5002AALX-00J37A0.

I am quite sure that all three drives are 7200 rpm, as I bought all of them new from Newegg in 2011.

The free version of HD Tune does not appear to offer the cache test.  Does any other free utility offer a cache test?

It is disappointing that WDC’s Lifeguard will not reveal cache, # of platters, etc.

I downloaded the trial version of HDTune.  The rotation speed was blank.  I did not see cache size anywhere, even though HDTune’s website promised that it was included.  I only ran one benchmark on the light drive:

                                        read                write

sequential                       32902 KB/s     25804 KB/s
4 KB random single        109 IOPS        341 IOPS
4 KB random multi          148 IOPS        274 IOPS

Not very useful, I think.