Evga 980ti problems/maybe problem with system?

[eatmykeyboard]

Good evening guys and gals,

I've been having a lot of trouble recently with my pc setup the specs are as follows;

I5 4690k @ stock
Evga 980ti with backplate @ stock
Asus z97-Ar mobo
8gb corsair vengeance lp ram
Evga 850w P2 psu
Windows 10 64bit enterprise.

Now I recently sent my GPU back for an RMA as it wasn't working properly lots of artifacts low clock mem speeds etc so upon receiving my new one I'm still having the same kind if problems.

Gpu usage in unigine heaven benchmark is 95-100% mem is 3506mhz gpu clock is 1316mhz but my Tdp is 40-50% meaning I'm getting next to no performance at all!
15-30 fps when realistically I should be maxing out close to 100fps+
This is all at 1080p.

It's the same with playing games. fallout 4, mgsV, witcher 2/3.

Now I've obviously I've changed the GPU, all the drivers are up to date.
Tried reseating countless times, unplugged and re plugged all cables.

Have yet tried my old gigabyte z97 mobo to see if it's the motherboard, but now I'm starting to think it's my psu?!

I need some serious help as I'm at the end of all the stuff I know!

 

[eatmykeyboard]

Cheers for reply, I haven't tried my other motherboard yet need to find some time to do it! All drivers and bios are up to date, changed pcie cable aswell tried all 3 pcie 3.0 slots still the same problem

It's pretty weird as I never had an issue with my amd 270 and a cheap 450w psu! Since upgrading the mobo and gpu I've had nothing but problems

 

[eatmykeyboard]

So I had a few minutes to take alook in the BIOS and tried the Asus overclocking software just to see if it would work as before I was getting vga red led when I tried with my other defective 980ti, now it's strange as it's ocd it's self to 4.3ghz, temps are fine and the 980ti has now started to work in the second pcie slot?! Full TDP, gpu usage 100% clocks and mem all fine could the fact my i5 is at stock cause a bottle neck on the 980ti???

Cheers guys

 

[eatmykeyboard]

Cheers for the advice guys, I had checked and made sure that epu and tpu weren't on, I do think the top pcie slot is defective but still wouldn't explain why my 980ti is only getting 20fps in unigine heaven bench. It will only work if my Cpu is overclocked? I did update to the latest bios 2501 but I believe they have bought out a new one since then so will give that a try once I finish my nightshifts!
Still need to try my other motherboard, and maybe see if I can check my other stuff out in my friends pc of around the same spec.