Memory usage 10GB of 16 GB installed

Win 7 x64 bit O/S on SSD (no page file)
Core i7 Sandybridge
16 GB DDR3

With 16 GB ram installed after booting up I'm consuming about between 1.7 - 2.2 GB of ram (with the usual programs & services running in the background). After a few hours surfing and performing various tasks, my memory usage climbs to 10 GB and stays there. Initially I thought this may a virus but after a thorough scan there's no virus present. Because the memory rise is so consistent and always stops at around the 10 GB mark, I'm starting to think this must be Windows 7 allocating the memory. If I re-boot at 10 GB, memory usage returns to under 2 GB when I reach the desktop. Any advice appreciated.

What's the problem with that observation, why does it matters?
And how are you measuring used memory?

That's completely normal. It doesn't matter if it uses 10 GB or you have 5 or 10 GB free RAM, the speed will be same. The more RAM you add, the more your computer will use, nothing wrong in this. If your computer ever needs more RAM for one specific thing/program, it will automatically care of that without you doing any action.

I recommend you to read this - Why It’s Good That Your Computer’s RAM Is Full.

1. memory usage at boot

2. memory usage after a few hours (surfing, using various programs, - then closing them)

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