Old PSU works with old Mobo/cpu, but not New mobo/cpu (surprise!)

[James_582]

Ladies and gentlemen, boys and girls. I present to you my conundrum.

Decided to give myself an upgrade today, So I went and bought a second-hand Intel i5-4690k, and a brand new gigabyte GA-z97p-d3 motherboard to accommodate my newfound processing power.

I assembled my to-be new rig Yet when I pressed the power button, It powered up, and powered down in a continuous loop.

Naturally, I spent hours and hours trailing through forums, blogs, posts, videos, ANYTHING I could find with solutions to problems related to my own... Sadly to no avail, my problem still persists.

Now after trying trick after trick to get the thing working, I concluded that the motherboard or CPU was acting up, so I took my motherboard & cpu back to the store where I bought them, asking if they could test them on a rig. Surely enough, they went ahead and tested the two.

And, they were both clean.

So from this newfound info, I returned home and started completely deconstructing my rig, to the point where only my motherboard, a cpu fan, and the PSU remained (Not even a whole CPU).

Powering up my Old motherboard with just a cpu fan yielded what I expected, a constant spinning fan, the motherboard clearly had constant power supplied to it.

However, powering up my new motherboard with just a cpu fan yielded the same results as I had at the start; a spin for a couple of seconds until it powered down, and powered up again in a very frustrating cycle.

From All of my testing I have concluded:
My new motherboard is not faulty, It functions perfectly fine in other rigs.
My new CPU is not faulty, it again functions fine in other rigs.
My PSU is perfectly fine too, As it powers my old motherboard perfectly.


..... So (surprise!) If my CPU, Motherboard, and PSU are all fine, perfectly working components, why wont they work together?

Specs:
Corsair cx750 PSU
8gb Corsair Vengeance DDr3 ram (2x4gb)
Asus GTX 1050ti (4gb)
Old CPU - Amd Phenom ii 965 BE (am3+)
Old MoBo - Asus M5a97 r2.0 (am3+)
New CPU - Intel i5-4690k (1150 chipset)
New MoBo - Gigabyte GA-Z97P-D3


Things I have tried:
Reseating all components.
Quadruple checking all connections
Removing all components one at a time to hopefully find a fault
Tried seating ram in every possible combination
Cmos battery reset
Cmos Jumper reset
Switching fans/heatsinks

I'm at the end of my tether, I'm going mad.

Any help would be appreciated!

 

[DRagor]

Could be BIOS mismatch - that CPU needs F5 BIOS, so if board would have lower version, it would behave just as you described.
Other then that, not (properly) connected 8-pin EPS or 24-pin could cause that.
But that closes the list of logical causes.

 

[Dark Lord of Tech]

Are you trying too boot with the HDD that has the OS on it from the AMD build on it , if so that's not going to work with a platform switch. You will need a clean install.

 

[cliffro]

Are you trying too boot with the HDD that has the OS on it from the AMD build on it , if so that's not going to work with a platform switch. You will need a clean install.

That could be an issue later down the road(after getting the combo to boot), but should not affect the pair from actually posting.

I don't know if it still works on newer boards, but I had an AMD Motherboard/CPU combo I ordered that was lacking the correct bios version for the CPU I ordered, I had to boot it with 1 stick of RAM so it would boot/POST and I could update the bios. Again not sure if that still works or if it ever worked on Intel boards.

 

[Dark Lord of Tech]

I have seen them not post several times.

 

[cliffro]

I have seen them not post several times.

I'm not surprised really, but most mismatching I've seen usually just ends in a BSOD.

 

[Achint2000]

This happened to me twice on my first build. It was a motherboard hardware fault, NOTHING related to the PSU (though the PSU was which put it in that faulty state at first). It'll start and instantly stop, start again and so on. It got fixed from warranty.

For starters, try a different PSU. Try your old PSU with the new build.
My CPU Fan keeps running even if I have no CPU and RAM but just the motherboard.

 

[Fallen93]

I have the exact same problem as yours, my PSU doesn't work with my old computer, but in my newer computer it works completely fine. And when I plug the PSU of my newer PC on my old PC it also works. So it's not a hardware problem I guess.