windows 7 - HDD takes a long time to respond from idle, but SMART tells me that spin-up time is fine

I have an HDD that I've been using for a while. It's a Samsung HD753LJ 750GB running on SATA.

According to CrystalDiskInfo it has a Power On Count of 5,174 and Power On Hours of 17,664. Not sure if that would be considered "old".

The problem is, sometimes when I've left the disk idle for a while, it will take an inordinately long time to respond, say a minute or more, and it hangs Explorer in the meantime. However, CrystalDiskInfo tells me that its spin-up time is nothing to worry about. The normalised value it gives is 75, and the raw value is 0x2080.

This problem has just cropped up since I've transferred it to a different system with a fresh install of Windows 7. One thing that I've done differently this time is I've enabled AHCI in the motherboard. Prior to this I'm pretty sure I've been operating off older legacy drivers.

Another thing to note is that I think the problem has improved slightly now that I've installed all updates on the system. Prior to installing the system updates it was constantly happening, but now it's only happening every now and then. It's still too often, though.

EDIT: I've just double-checked, and I've swapped the SATA cable and SATA ports, and the problem still exists.

Answer

I figured out the answer - my best guess is that running an HDD in AHCI mode when it's not capable of running that mode caused this behaviour.

I physically moved the drive into my Ubuntu server to backup my files before the drive died - long story as to why - and I discovered that the drive was performing just fine. I looked into the BIOS on that machine and found it was still running all drives on IDE.

I went back to my Windows machine and switched SATA ports 4 and 5 to IDE mode, then plugged the HDD into port 4, and the problem is gone.

I assume the problem was that my motherboard was expecting to see an AHCI drive, but when that didn't work it fell back to IDE after a timeout period, and then the drive performed just fine. That's why when the drive went idle, there was a time delay before I could access it, but the SMART diagnostics reported no problem with its spin-up time.

My motherboard is a Gigabyte 970A-D3P with BIOS version F5. I assume that this behaviour is somehow related to the way that board is programmed, but I don't really know. I'm just putting the model number into this answer in case it helps anyone in the future.