How do I know when to upgrade RAM in Vista?

Task Manager: XP on the left, Vista on the right.

On XP, I would check to see if Peak Commit Charge was approaching Total Physical Memory. When Peak exceeded Total during normal usage, the page file gets hit harder and performance degrades. I would know to recommend a RAM upgrade.

As Jeff explains, Vista uses RAM differently.

How do I read Task Manager in Vista to objectively determine if it's time to upgrade (i.e., the page file is getting taxed)?

Solution 1:

I recommend using the Reliability and Performance Monitoring Tool to see if your system is memory starved, specifically the memory section. Look for hard faults/sec:

A hard fault (also known as a page fault) occurs when the page of the referenced address is no longer in physical memory and has been swapped out or is available from a backing file on disk. It is not an error. However, a high number of hard faults may explain the slow response time of an application if it must continually read data back from disk rather than from physical memory.

Solution 2:

When you can afford it, buy it. You always need more memory, especially in Vista.

Solution 3:

Try using resource monitor and looking at the percentage of physical memory used.

Solution 4:

FYI You should be aware that there is a 4GB ram address space limit in 32bit versions of XP and vista. If you want more than 4GB, you need to use a 64bit version of windows.

For full details please refer to this Microsoft MSDN article

So my approach has always been to install 4GB of memory in a 32bit OS by default.