I've had an intermittent problem on this (W7 64) system for eons in that, from time to time, the HDD light will come-on solidly and the system becomes 'unresponsive' whilst it's on.
I've run diagnostics and resource monitors and NOTHING is accessing the disc more or less than normal at the time - CPU usage is usually low too. This 'freeze' lasts anything from 2-3 seconds to 20 seconds and it's bloody annoying (and highly intermittant - sometimes 10 times a day - sometimes not for days).
I've disabled and changed allsorts of settings/programs/other stuff but nothing has resolved it thusfar. I even swapped the HDD (copying Windows to a new drive) and that didn't solve it either (I also changed the cable and the SATA socket!)
Tonight I think I might finally have an idea what's causing it tho - write-caching. W7 has 2 separate options in relation to this (Device Manager/HDD/Properties/Policies) - the "Quick Removal/Better Performance" options - which I believe control what caching Windows does - and the "Enable Writing Caching" policy which I think controls caching on the drive itself!?
As an experiment, I disabled the latter - and interestingly enough, doing it caused the system to do a 'freeze' - the symptoms in the Resource Monitor were identical (100% HDD usage - almost no IO or CPU) for about 15 seconds - this may just be a fluke but only time will tell.
What I wanted to ask tho is - does anyone know the innards of those 2 policies - the significance of the latter option (HDD?) over the other policies (Windows?) and what the upshot of disabling them might be?
Note: I've no desire to eject the system HDD - nor is it in any way a bottleneck to the system - e.g. I don't think I'll miss the caching!?