Using more RAM than normal

Ok so monitor my hardware religiously, and I have been noticing this problem over the last month or two. Normally at start up Windows uses 33% of the 4GB of RAM. Its been that way for the past two years. Recently though Windows has started using 45-51% of RAM after booting up with no other programs running (besides the things i have set to auto start). I have installed new 1-2 programs at the most in the past 2 months (one being Dropbox, cant think of anything else). What I am getting at is that as far as I know there is nothing new installed that would be using so much RAM. Upon looking at the processes the only thing out of the ordinary I see is one scvhost.exe using about 111MB of RAM (which is abnormal but not enough to increase RAM usage by 20%), I can lists its services if need be. I have no idea what could be causing this increase in RAM usage. I scan weekly with Malware Bytes, Spybot S&D, and Microsoft Security Essentials (lol) and none of those have turned up anything.

Another thing I have noticed is that upon startup it uses 45-51% of RAM but if I log in, and then put the computer to sleep, then wake it up after waking only 17-23% of RAM is used. This is something I have never noticed before because I used to never put my PC to sleep, only recently have I started doing that to save money on the power bill. IDK if its related or not, but as of right now I have resorted to starting my PC, putting it so sleep immediately and then waking it back up just so I can have the most available RAM.

Any suggestions as to what is causing this? I am at a loss.

PC Specs:

Windows 7 64bit Ultimate SP1 (build 7601)
i5-750 (first gen quad core) @ 3Ghz
4GB Gskill DDR3 1600
Asus mobo
Radeon 6870
OCZ 730W psu
2 HDD's