HDD very slow, but all tests OK??

I've had some computer behavior that I don't understand.
Perhaps someone can explain what I'm seeing.

Over the past year, I've had two desktop computer systems, both 64 bit windows.

The first system had a WD 300Gbyte Velociraptor disk. It also had a defective motherboard that I replaced. But after the motherboard replacement, the system would go into 30 second long disk delays in Win7, several times a day, generally related to a context change like switching windows. Most processes in windows would stop, and there would be 30 seconds of furious disk activity, where I could move the cursor around on the screen, but nothing else would happen. After 30 seconds or so, the system would recover and be fine.

I tested everything, but could never find any hardware issues or any indication in the system logs as to what the system was doing in these periods of disk activity.

Eventually, I backed up the Velociraptor disk (which was my C disk), and replaced it with another hard drive.

The problem went away.

So then I put together a similar, second system. I thought, well, maybe the problem with the first system was not the Velociraptor disk, but related to some Windows problem that Microsoft had fixed with an update. I did a long re-format of the Velociraptor drive, and did an extensive set of test on it --- all tests passed, and the SMART values were all OK. So, I figured the drive was OK, and I put it in the second computer system (all other hardware parts different from the first), and set up the system.

At first it was OK, but after a few weeks, it again started showing the 30-second disk delays, when switching contexts. I defragged the disk, I tested it --- nothing showed up in the tests, nothing helped. Note that the 300 Gig disk was only half full --- I was careful to move all my personal stuff to other drives on the system.

So now I've backed up the second system and re-installed it on a new C drive. The problem has again gone away, and has been gone for a week now.

How can a hard drive that tests OK cause delay problems with Win 7? Because that's what I seem to be seeing. Do you think it would be worth sending the Velociraptor back to Western Digital for testing?


Tony

How old is the WD drive? How long have you used it?

Just so you know, I had an WD System drive that started suffering Thermal failure and didn't seem to show any drive issues until I came home one time and saw my system had restarted and seemed to be stuck on the BIOS screen. Upon further investigation, the system would try to boot, but was extremely slow in doing so. Result - Drive was failing from overheating (Let it cool, you can access it for a bit of time, but eventually, it completely failed and couldn't pull anything off it)

I do know that for some systems, like Dell, there is a BIOS drive diagnostics. That is how I determined my drive was having serious problems like showing access errors. Some of the software tests focus more on physical disk platters or data on the disk but not on other factors of the disk drive.

The Velociraptor in question was new last year.

The temperature monitor did not show overheating.

Have you tried to back up the drives contents and then rezero the drive using the diskpart commands?
SSD / HDD : Optimize for Windows Reinstallation

Often times when you change motherboards it's either required or simply works better to rezero the drive and then reinstall the Op system using the new motherboard.