Dell Optiplex 3020 SFF not booting?

Hello there. I have been having issues with my machine as today it decided to not work. I have tried to reseed all of the components on the motherboard and power supply cables and that that has not solved the issue. The computer keeps rebooting constantly so it is very difficult to read the post code on the power LED. Any thoughts? 

Specs:

CPU: i5-4590 @3.30ghz 4 core 4 thread 6mb L3 Cache

GPU: EVGA GTX 750 TI

Motherboard: Dell 3020 SFF Motherboard

RAM: 16GB Timetec DDR3L-1600 at 1.35V

SSD: Inland Professional 256GB SATA SSD

Cooler: Dell Stock Cooler

PSU: Dell Stock 255w Dell Optiplex 3020 SFF PSU