Installed new CPU, Endless bootloop, no beepcodes

[Profatoe]

Exactly what the title says, I've tried most things to fix this but the problem still proceeds,

PC will turn on for exactly 3 seconds then shut off then repeat, can't break this boot loop,

please help, if you have questions about the problem please ask, I don't have the money to be
Buying new parts and I hope it doesn't come to that.

Everything worked fine before I swapped CPU's, don't have a different PC to check which part is the issue, not getting any beeps at all from my case speaker for error codes

Things I've tried:
- Reseating CMOS battery
- Taking out all RAM & leaving in just one stick
- taking out CPU to check for bent pins or damaged connectors
- making sure I had enough cooling and wasn't getting a thermal shutdown
- taking out graphics card
- reseating all cables
- Updating the bios from a USB

Things I haven't tried:
- unplugging everything but essentials
- putting in a different haswell CPU
- trying a different PSU

Specs:

New CPU: i5 4690k
Old CPU: i7 4770k (reason for swapping is because I need the money for a new graphics card)
Mobo: Gigabyte z87x-d3h Ultra-Durable
PSU: Ultra 650w PSU (pretty old but worked fine before I swapped CPU so I doubt it's this)
RAM: DDR3 Kingston hyperX fury black

If you have any other questions I will be answering this frequently, please send to people who know about PC's too, this has been doing this for almost a week

 

[Profatoe]

Edit: PSU is fine, just jumped it to test, sure it's the bios now, can someone tell me how to update a bios when your PC won't boot? Do I need to switch back to old CPU to do it?

 

[Paul NZ]

If the BIOS doesnt support the new cpu then yes install the old one flash it then try

 

[Profatoe]

Didn't mean to -1 that, with the @BIOS feature on the z87x do I need to flash it still?
Will try your solution this weekend with my friend who has the CPU, a lot of hassle switching all the CPUs around but hopefully it worked! If not anymore ideas?

 

[Paul NZ]

Looks like the 4790k needs BIOS F8. The other needs F7.

So if F8 isnt on it now, it needs to be flashed to F8

 

[Profatoe]

Looks like the 4790k needs BIOS F8. The other needs F7.

So if F8 isnt on it now, it needs to be flashed to F8

Yup I'll try that, if it works then everybody with the same issue will now have a solution! Thanks

 

[Profatoe]

Looks like the 4790k needs BIOS F8. The other needs F7.

So if F8 isnt on it now, it needs to be flashed to F8

Yup I'll try that, if it works then everybody with the same issue will now have a solution! Thanks

 

[Profatoe]

Solution: Updated bios so that it could support the newer generation CPU, Had to put the old CPU back in to do this, used the @BIOS tool from gigabyte