Went ahead and bought this one at my local CC. Installed it last night, and yup it was my old PSU that was the problem. Thanks for the recommendation. There's a couple of my case fans that don't quite reach their sockets now, so I'll have to grab a couple of extension cables (the Corsair PSU only comes with one molex cable which is a shame), but other than that I got everything hooked back up and my PC booted up.