RAM is reserved, cant use it? 4GB

[Luke_Live]

i have 8 GB of RAM in my Mobo, But it says only 3.90 GB is in use and 4.10 GB are being reserved. How do I get all 8 GB to be used. Is it because my ram is in a slot in the mobo that is dead? (but it says on Task manager that 2 slots are used out of 4, so idk)

 

[Luke_Live]

Just in case someone with the same error comes by here, I fixed the problem. I opened up my pc, took the ram out. Cleaned the ram slots on the mobo with a can of air, and the ram itself with the air (but not too close) and a clean paintbrush. (I bought paintbrushes SPECIFICALLY for PC cleaning. DO NOT use paint brushes that have been use with paint before. although if they are clean they might work, but better safe than sorry!) Then I put just 1 of my 2 sticks of ram in. Plugged my PC back in. Checked to see how much was reserved. I had 3.9 GB Usable and only 103 MB reserved. Then I unplugged my PC. Added the 2nd stick of ram (in the same slot as it was before, I put both sticks into the blue slots on my mobo, and left the 2 black empty.) Then I booted up my PC again, and I had 7.9 GB usable out of 8 GB. Alot better than 3.9 GB usable out of 8.