PC froze now won't boot

Hi, I have a gaming PC that I built about two years ago. I was playing Minecraft (CPU and memory intensive) and the computer froze and wouldn't respond to anything including ctrl + alt + del. Its never done this before so I held down the power button to turn it off but now it won't turn on again. When I press the power button nothing happens, but when I turn the power supply switch off and on and press the power button, the fans will spin and lights will come on for half a second then turn off. I thought maybe the CPU had overheated but after waiting a while it still didn't turn on. I also tried clearing the CMOS and cutting the power, neither changed anything. The motherboard standby light is on.

I searched around and I think it might be a bad power supply, any ideas? Thanks

My specs:
PSU:
FirePower ModXStream Pro 600W 80Plus Semi-Modular High Performance ATX PC Power Supply 600MXSP
SSD:
Intel 330 Series Maple Crest SSDSC2CT120A3K5 2.5" 120GB SATA III MLC Internal Solid State Drive (SSD)
Motherboard:
ASUS P8B75-V LGA 1155 Intel B75 SATA 6Gb/s USB 3.0 ATX Intel Motherboard
RAM:
Patriot Intel Extreme Master, Limited Edition 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model PVI38G160C9K
CPU:
Intel Core i3-3220 Ivy Bridge Dual-Core 3.3GHz LGA 1155 55W BX80637i33220 Desktop Processor Intel HD Graphics 2500
Video Card:
MSI R7770-PMD1GD5 Radeon HD 7770 GHz Edition 1GB 128-Bit GDDR5 PCI Express 3.0 x16 HDCP Ready Video Card
Windows 7 64 bit
 
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