New pc freezing up/ not responding when multiple programs are opened. Please help!

[Loose1eaf]

Over this weekend I built my brother a computer. His specs will be below. And after installing over 200 updates for windows 7 we thought that all the glitching would be gone. But when he has steam running with a tab or two open of chrome everything stops responding, even explorer.exe stops responding at times. When he is able to get into some games his pc will run Nosgoth maxed with not a problem, but runs Rust at 30fps and lower. The freezing happens most when something is downloading or he is playing a game and he alt tabs to do something else. I am thinking that this is due to his ram being bad or just a bad install of windows since his pc did get shut off during a small windows update but when it was turned on again the update resumed right at the same percent. We think it is a windows issue and we should just re install windows? We have run ram tests as well which came back with no problems. His specs are
Gpu- asus gtx 960
Cpu- amd fx-6300
Ram- gskill 8gbs
Psu- Cooler master gold cert 500w
Mobo- Asus A97 m5 AM3+
Any Ideas will be tested and greatly appreciated!!
An update on this! He just played some Nosgoth and his frames were ok sitting around 50s and dipping into the 30s. Which a 960 is the same as my 770 and I run that game with v-sync and maxed out at solid 60 fps. After the game he checked his hardware monitor and the gpu was at 99% use but his temps were fine.

 

[digitaldoc]

It sounds like all the Windows updates installed.

Did you update the graphics drivers to the latest?

Also, run CCleaner, and CleanMem.