There are issues form both the hardware environment and the software environment.
For the Software environment, install Service pack 1 and all other windows updates. Otherwise the system will remain vulnerable to threats.
Code:
Windows 7 Kernel Version 7600 MP (4 procs) Free x86 compatible
Product: WinNt, suite: TerminalServer SingleUserTS
Built by: 7600.16385.x86fre.win7_rtm.090713-1255
For the hardware environment, if you continue using mismatch RAM, no further troubleshooting is possible. Remove the additional RAM that you applied later and see how the computer works. Let us know.
My Computer
At a glance
Microsoft Windows 10 Pro Insider Preview 64-bitIntel(R) Core(TM) i3-4130 CPU @ 3.40GHzCorsair Vengence 4GB x2 (8.00GB Dual-Channel ...2047MB GeForce GTS 450 (ZOTAC International)