Computer won't boot into BIOS keeps restarting every few seconds

[Kaasfarmer]

Hello there folks,

A week ago I decided to upgrade my computer.
Got myself this setup:

Intel i7 4790k (stock cooler, yes I know will be replacing that )
MSI Z97 gaming 5 - Motherboard
MSI gtx 970 4G - GPU
2x 6GB DD3 RAM (not sure what brand)
2 TB HDD
Cooler Master 700W - PSU
Windows 8.1 - OS

The problem is that my computer worked for like a day. After playing some Battlefield Hardline it crashed, and it kept on restarting without ever getting into the BIOS.
Before it did this, I did a stress test and the CPU wasn't getting hotter than 73°C.
Brought to the local PC shop and his first conclusion was that the Motherboard was damaged. Returned it the shop where they told me it was fine, they managed to install windows without any problems. The guy from my local PC shop also concluded:

PSU is fine,
GPU is fine,
RAM is fine, and no short circuit in the case.

I can't really imagine that the CPU is broken or overheated because the computer would shut down before that happens (right?). Other than that, the fans are working and the airflow is good.

Hope you guys can help me out here, that would be great
(English is not my first language, so sorry for any mistakes).

 

[Thelps]

You may want to try reseating the CPU Cooling Unit. Constant system restarts are often indicative of an overheating CPU. I know you've ruled this out with your previous tests, but it's worth confirming. If you get a successful boot, check your CPU Temperature using the BIOS' temperature. The i7 4790k is noted for running particularly hot with the stock cooler. A 3rd party cooler is strongly recommended.

Reattach the 8-Pin CPU Power Connector and the 24-Pin ATX Motherboard Power Connector also. A bad connection can result in erratic system behaviour.

Did the guy at the shop test your PSU in a different system? Sometimes system restarts can be attributed to an underpowered or 'burned out' PSU with damaged circuitry. This is quite unlikely, however. Your best bet is to try a different component with the system to see if you experience the same problems or not. PC repair shops may allow you to test using their spare components. Alternatively, borrow from a friend/colleague.