BSOD Error When Playing Multiple Games

my computer is recently crashing, I recently had some work done to it hardware wise and they had to do a fresh Windows 7 install because of all the hardware changes that Vista couldn't handle. They said if you do a lot of hardware changes, especially the motherboard you'd have to do a fresh install of Vista, and I said just do Windows 7. So a month it was working wonderfully on extensive games and recently maybe within this week my computer would randomly when loading games crash to the motherboard splash screen. Then when my computer starts up I see an AMD popup, and a Windows has recovered from an unexpected crash.