Computer randomly freezes while playing games.(no bsod usually)

[champkill]

My computer randomly freezes while playing games, a soft humming noise will come from the machine itself. The freeze is usually just the apps(meaning that i can like minimize the windows and click stuff on desktop) and is usually signal by browsers not opening webpages. Sometimes it will freeze completely and I will have to restart it. This problem has just recently started occurring, and I've had this computer for around 4 years.

Specs:
Cpu: Intel i5 3570k 3.4 ghz
Motherboard: Gigabyte Z77X-UD3H
Ram: Corsair 8gb ddr3 1866
GPU: NVIDIA GeForce GTX 460

 

[AstaLaVista]

All windows updates up to date?

Audio and video drivers updated from Manufacturer as well?

Perhaps its time for a Bios update?

Perhaps with age the pc does not like it when you alt out of a game... have you tried playing said games w/o doing this?