To make a PC faster, a reader moved its operating system from a hard disk to an SSD. But the reduced storage space is causing problems for Windows. Our Helproom expert explains what to do.

QUESTION My PC was taking a long time to start up, so I supplemented its 500GB hard drive with a 120GB SSD on to which I installed Windows 7 Ultimate and my frequently used programs. Once set up, I had around 20GB of free space on the SSD, and startup was much faster. I now find myself constantly monitoring the SSD, however, as restore points, Windows updates and program installations all default to it. How do I go about changing the default drive for such items from C (the SSD) to D (the hard drive)? John Munro

HELPROOM ANSWER The situation you describe illustrates why we steer the average user away from purchasing systems with small-capacity SSDs. We regularly see PCs with SSDs only half the capacity of your 120GB model – running out of space is inevitable without careful management.

If your motherboard supports Intel's Smart Response Technology (only those with a Z68 Express chipset do), this may offer a better use for your SSD. Here the SSD is in effect invisible to the user, and used as a high-speed cache to boost operation of the hard drive.

Smart Response won't provide as much of a speed boost as installing your OS and programs on an SSD would, but it will accelerate launch times for your frequently used files and reduce your boot time, without you worrying about it filling up.

If you can't or don't want to use Smart Response Technology, you'll need to make sure that Windows uses your hard drive instead of your SSD to store temporary files, system files and downloads. First, move your Windows swap file from drive C to drive D. This should get back a few GB immediately.

If you're not using Windows' Hibernate function, disabling it will bring back another large block of space. Simply open an elevated command prompt (click Start, type command, right-click 'command prompt' and choose 'Run as administrator') and type powercfg –h off. To restore Hibernate, instead type powercfg –h on.

When installing a program, you can simply edit the install location by substituting the 'C:\' with 'D:\'. If you want Windows to do this automatically then you'll have to do some Registry editing, but be warned that this can cause problems with existing shortcuts that will now point to D:\Program Files. We advise against this, but have provided instructions should you be adamant that you want to change the default setting.

To permanently change the default Program Files folder click the Start menu and type regedit, then run the application from the search results. Browse to 'Hkey_Local_Machine Software Microsoft Windows CurrentVersion'.

Double-click the string 'ProgramFilesDir', then change the Value data from 'c:\program files' to 'd:\program files'. If you're running a 64bit version of Windows, repeat this change in the string 'ProgramFilesDir (x86)'.

Another way to get back some space on drive C is to move your temporary folders to drive D. Hold down the Windows key and press the Pause button to bring up the System Properties dialog box (or select System in the Control Panel). Choose 'Advanced system settings' and select the Advanced tab. Click the 'Environment Variables' button at the bottom.

Scroll down the System variables pane until you reach 'Temp'. Double-click this and change '%SystemRoot%\Temp' to 'D:\Windows\Temp' or another folder you've created on the hard drive for this purpose. Repeat this procedure for the TMP variable.

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