There are three times during which you computer can detect bad RAM:

1. Boot up testing runs a very quick test over RAM, plus a more comprehensive check on a tiny bit of RAM used during the boot process. Any bad RAM found here will be disabled until the next time you turn on your computer.


2. Write errors occur when a program tries to write to RAM. All well-written programs report these errors to Windows and ask Windows for permission to write to another part of RAM. Windows keeps track of these errors and tries to avoid using that part of RAM again.


3. Read errors are the the worst–they occur when a program tries to retrieve something it previously stored in memory. When it gets an error and realizes it won’t get the data back, the program may crash. Other programs print obscure errors. Some programs may continue to try running and fail minutes or even days later for no apparent reason.

All three errors can guarantee that your computer is perforing slow. Testing and write errors force Windows to keep track of bad RAM (which ironically takes up more RAM) and to assign RAM to programs in smaller, slower blocks. Read errors slow you down by forcing you to recover from program crashes and to deal with strange errors. more information visit this site http://bdcomputersolution.blogspot.com/