WIN7 x64 - Uses all available RAM, runs slowly

Hi all, pardon the newbie question. If this has been answered already please point me that way? I did do a search but found nothing to help.

My system is a home built, Core I7, 8GB RAM, Radeon 560 TI with 2GB VRAM. Recently upgraded from 4GB RAM.

I was having this same issue with 4GB of RAM. After the computer has been on a bit (hour or two) the memory usage will approach 90% and upwards and things will start to run slowly. I close all active programs, kill all non-essential background programs (dropbox, steam, printer software etc). I look in my processes and no way does it all add up to nearly 8GB of memory.

So my question is, how do I get my computer to run faster? I know WIN 7 uses memory differently than XP did, and I don't care if it wants to use all the RAM, as long as it will run quickly. The problem is, it runs slowly.

I have WIN 7 x64 ultimate, I have ESET security suite and show no viruses. Problem goes away after I reboot, but returns over time.

If I can provide more info please let me know.

How can I determine which one it is (other than trial and error)? Nothing really shows up as "large" in task manager. Firefox is by far the largest, but when I close it out it doesn't really fix the issue and it is rarely over 300mb in size.

Is there any way to reclaim the memory other than rebooting?

Check your Memory IO Operations. They are available in Task Manager view options. Also check your CPU usage. It sounds like a buggy application. If your application uses .NET framework, update to the latest .NET service pack.