I am busy analysing my system to find out exactly where the performance bottlenecks are, mostly from a gaming perspective. I'm pretty sure my CPU is the limiting factor in most cases. To confirm this, I need a very lightweight CPU monitor that also keeps historical data, and won't influence the test. Process Explorer is brilliant, but too CPU intensive for my liking.
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Gigabyte has a tool that can monitor usage, although it too may be too heavy. I've used it and it can keep a log file. I'm not sure if you need to have a gigabyte board.