Computer recognizes 8GB of ram, but only uses 30% of it?

Question

Windows 7 Ultimate x64
Intel Q9550
ATI radeon 5770
P5QPL-AM ASUS motherboard
OCZ 8GB (2x 4GB) Platinum series RAM. pc2-6400 DDR2, 240 pin, non ecc, unbuffered
I have installed 8GB ram into my computer. Both my BIOS and system properties state I can use all 8GB of it. However- even when I put my computer under huge strain, I've never seen it go higher that 30-31%. It idles on about %20, so that means when I put strain on it, it only ever goes up by %10! I have not set a limit in msconfig either.
It's frustrating me why my computer isn't using all my ram. If anybody has any suggestions, let me know!
Here's an example: I open photoshop with a huge canvas (A0), and went crazy with a large brush. I've allowed PS to use %75 of my memory. PS lags heavily, yet my ram will not budge higher than 30-31%. Here is a screenshot of it. The ram is the steady blue line.
I would be extremely thankful if anybody could share any thoughts/information. Thanks

Answer 1

Okay, now that we've established that Photoshop is using all the RAM you've given it (which can be a lot higher on an 8 GB Windows 7 system, by the way; as much as 90%+), let's discuss the root problem you're having:
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Mistle22 wrote:
...I open photoshop with a huge canvas (A0), and went crazy with a large brush...
...it would stop lagging and run smoothly...
... my Photoshop lag problem ... still persists and makes it impossible for me to work on A1 and (rarely) bigger canvases.
You've been vaguely referring to a "lag" problem...
Reading between the lines, I believe what you're saying is that if you paint on a large canvas with a large brush, you're experiencing some delays and non-interactive activity.  But no one here is a mind reader, nor are we sitting with you seeing what you're seeing.
Please take the time to specifically answer each of these questions:
Exactly what version of Photoshop are you running?
How many pixels in your "A0", and what is the bit depth?
What size brush (in pixels), and how hard (in %)?
What is the brush Spacing?
Is it one of the fancy new brushes?
Are you painting with a tablet or mouse?
How far behind does Photoshop get (a fraction of a second? seconds?)?
Do you see the same performance issue with OpenGL enabled or disabled in Edit - Preferences - Performance.
Have you updated your video driver to ATI's latest 11.2 release from the AMD web site?
A little more detail would help us help you.
FYI, I just created an A0 sized RGB image at 150 ppi (7020 x 4965 pixels), 8 bit depth, and painted perfectly interactively on it with a 500 pixel round brush with 1% hardness and 25% Spacing.  However, there is a visible lag of up to about 1/2 second if I increase the brush size to 2500 pixels.  This is on a VERY powerful workstation with ATI 5670 card.
-Noel