Hello.  I am running Win 7 64-bit.
 
I had to re-install my computer software and OS.  After cleaning all HDD using Diskpart and making partitions, I just finished installing the OS, loading the MOBO drivers, and updating Win 7.
 
No programs are yet on the computer.  Yet Windows is telling me that 44 GB of space on the C drive have been used.
 
44 GB of space taken up by Win 7 alone?  This seems like a lot of disk space just for the OS
 
The Microsoft site tells me that Win 7 64-bit needs 20 GB of disk space.  Yet on my computer, it is taking up twice that amount of space.
 
Can anyone tell me how I can reduce the size of Win 7?  I have already reduced the amount devoted to System Restore to 3 GB.
 
 

Maybe the Page File size?
 
It's been since XP that I have messed around in the bowels of Windows - but maybe that is something you could adjust.
 
Also, look for hidden folders - try to find out where exactly all of this extra size is coming from, and maybe it can be looked up online and adjusted.
 
Bob Bone
 

There is software for checking disk use:
http://sourceforge.net/projects/windirstat/

Hello.  OK, so far I have only installed the OS and updated it, and loaded the MOBO drivers on this computer.
 
Data from My Computer:
C: drive = 42.8 GB
Folders on C drive:
- Intel = 1.77 MB
- PerfLog = 0 MB
- Program Files = 406 MB
- Program Files (x86) = 322 MB
- Users = 191 MB
- Windows = 15.4 GB
Those are the only folders currently on the C drive.
 
So this is curious.  Windows tells me that in aggregate, 42 GB of the drive space is used, but if you add up the size of all the folders on that drive, it comes to around 16.2 GB of drive space.  So something is using around 25-26 GB of drive space, but I don't know what it is.
 
I would prefer to have that drive space for my own uses.  Can anyone tell me what is using all that drive space, and can I do anything to reclaim that drive space?

Check the size of the restore points.
 
There may also be a hibernation file which I believe is roughly the size of your memory. You need to enable hidden files and the protected files to see it (in Folder Options control panel).
 
You can disable it with "powercfg -h off" in an admin cmd prompt.

Aha!!  OK, I think I got it.
 
So, after:
1) changing the virtual memory/page file to Min: 1024 MB and Max 1024 MB on the C: drive
2) turning off Hibernation (as per arachnaut above - thank you arachnaut)
 
the amount of used space on the C: drive is 16.5 GB - approximately what I expect from the size of the files on the C drive.  I've reclaimed over 20 GB of HD space!
 
On this computer, I have 16 GB of physical RAM installed.  Some suggest turning off the virtual memory altogether when there is 16 GB or more physical RAM installed.  I have mine set as above (I read that allowing Windows to dynamically grow and shrink the page file size results in fragmentation of the page file and degrades Windows performance, so I set my page file Min and Max to the same 1024 MB).  Has anyone success with turning off virtual memory when using 16 GB physical RAM?
 
 

Turning off virtual memory can be done with any amount of RAM, it's just that with 16GB+ there's less chance of Windows suddenly finding itself in an "out of memory" situation, which really upsets it. Some software also expects to see a page file, so it's not alwayts a good idea to get rid of swap entirely.
 
A fixed amount of virtual memory is the way I go, a dynamic page file can get horribly fragmented. With less than 16GB RAM I set it to twice or 1.5x RAM, 16GB+ I just set it equal to the amount of RAM. To prevent swap file fragmentation I install (just) Windows, switch of virtual memory then defrag the C drive. THen swith virtual memory back on again. With any luck the swapfile than ends up a contiguous file.
 
Another approach is to creat a partition at the start of another drive (ideally one that won't be used for data access during high disk bandwidth requirements like spooling multi-channel audio or video, say a drive used for backups only) and create the swap file in that partition. THat way it's on the fastes part of the drive and won't be sharing bandwidth with the system C drive.
 
With SSDs rather than HDDs it seems to make little difference where the swap file is, so I leave it on C.

I set my swap file (page file) on a separate partition from the Windows drive.
 
I pick one of my other physical drives and partition it in two parts - the top fast part is set to size 50 GB and name it TEMP and set the rest of the drive up for normal stuff.
 
Then I set my swap file in that small partition along with the TEMP path files and stuff like Windows search, Internet Temp files, Google Chrome cache, etc.
 
Even if you don't think you need a swap file, I think it's a good idea to have one for system performance reasons.
 
If there is no swap file on the boot drive you may see an error message about Crash Dump initialization error.
You can ignore that, it expects to see something on the boot drive.
 
Also, I set the Min and Max size the same so that it doesn't shrink and grow and get fragmented. The older rule of thumb was to set the size to about 150% of your RAM, but with multiGB memory sizes that's way too much. A few GB would probably be fine. You can use the resource monitor or task manager to see if the size is wrong (if it fills up right away after a boot).
 
To clean it up:
 
1) turn off paging and reboot so it goes away
2) set it up and reboot to make a new one.
 
If you have Windows 8 or 8.1 you can delete the swapfile.sys and use mklink to point it to that Temp partition. It's used by the Start screen apps for something. That may be hard to delete, I use a Linux boot tool to remove stubborn things like that, or you can mess around with system permissions.
 
 

Thank you arachnaut and tlw - very helpful information.