I had this situation but when I checked I found the System process was hogging my disk!
In the above you can see my Disk at 94% it's all because of the System process... but what to do?
I looked around and there are many possible solutions. A couple I found actually made a difference so I'm going to explain them here. However, don't forget, if what worked for me doesn't work for you, keep searching! I don't have all the answers, I'm just sharing what I've discovered worked best for me.
Change the Virtual Memory
Windows 8 is supposed to work well without changing the virtual memory but I found a tip on the web and it has helped me. You must set the initial virtual memory size to your physical RAM size in megabytes. Set your maximum size to twice your physical RAM. In my case I had 8GB or RAM, so I set my initial to 8192MB and my maximum to 16384MB. You should set yours according to how much RAM you have in your computer. Remember that 1GB = 1024MB.
- Control Panel | All control panel items | System
- Click Advanced system settings
- Under performance, click on Settings
- Click the Advanced tab
- Under Virtual memory, click Change
- Deselect (disable) Automatically manage paging file size for all drives
- Select C: (where Windows is installed)
- Click Custom size
- Set Initial size equivalent to your RAM size in MB (in my example above I set it to 8192MB, that's because I have 8GB of physical RAM) - see the graphic below
- Set Maximum size to twice of your RAM size in MB (in my example above I put 16384MB because that is 16GB, double my physical RAM size)
- Click Set
- Click OK three times
- Restart your system
My PC is running Windows 8.1 but this will surely work with Windows 8 and I think even Windows 7 would benefit if you are having the same issue.
SuperFetch is supposed to speed things up (for conventional hard disks, not for SSD). However, I've found that disabling it has reduced the disk activity in my Task Manager! After changing your virtual disk settings (above), if you still have a problem this is worth a try (you could always switch it back on later if it doesn't help).
Press Windows key and R (to get the Run dialogue box)
Type services.msc and press Enter
Find Superfetch in the list, double click on it
Change Startup type to Disabled (as above)
Click Apply and OK
For more details on this and even some other solutions, click this link:
NOTE: I've found that with SuperFetch (SysMain) disabled, ReadyBoost is disabled. Previously when I had only 4GB RAM I had found that ReadyBoost helped (click here to learn more). It seems to be a matter of swings and roundabouts! Now with 8GB RAM it seems SuperFetch and ReadyBoost are not helping. Essentially what this means is that you really need to experiment to find out what works best for you. It depends a lot on the balance of RAM and the applications you are using.
Stop Windows Search
One of those that I found useful was to turn off the Windows Search service. Here's how:
Press the Windows key and X and A (Win+X+A)
The Command window will appear:
Type NET STOP "Windows Search" [Enter]
Or you could do it through services.msc where there's more control.
There are a lot of other solutions, here's a link where you can find more discussion:
For me changing the Virtual Memory helped a lot. My disk usage is much lower and my PC seems faster as a result. I had upgraded my physical RAM from 4GB to 8GB. I wonder in Windows had not realised and that was the reason? In any case I think changing the virtual memory is well worth a go.
I've also found disabling the SuperFetch has helped but from what I've read this might not always be a solution for everyone. It's something to try.
If you are desperate then try stopping the Windows Search too - as explained above. I did find it reduced my disk usage for a while. This process will restart itself, it could be a temporary measure until you find the real reason.
For more information click the link in the Reference section below. If you can see a specific process is causing the trouble then do a search on Google for it and put the words "disk usage at 100%" and you may find some words of wisdom out there. Feel free to add your experience to the comments :-)
Many thanks to Arpan Kashyap for this tip!
Also, for Superfetch see: