New power supply problem

[Destius]

I bought an rm750x psu from corsair yesterday connected everything PC ran booted and after going in windows it worked for 5-10seconds and then I got a black screen. The monitor was not getting any signal but the PC is working properly I can hear Skype turning on by my headphones and no matter what I do it does not show anything. The PC does not turn off tho.removing my GPU and using my motherboards inputs for my monitor fixed the problem but when I try to use the GPU it shows 10sexonds of image and turns off. My GPU does need pcie power so that is one of my thoughts as to why it has problems. Apart from that I don't know what the hell is going on pls help thanks for your concern.

PC build.

A10-5800k

Rm750x

Rx 470 8gb

Gigabyte f2ax88xm-hd3 

128gb Ssd corsair

2 hdd

[MVPernula]

You have an older motherboard, it might cause the problem.

It most likely doesn't serve enough juice through the PCI-e slot.

 

And it might be a bad GPU.

[Altecice]

I am suspecting that its the GPU and not your PSU. 

[Destius]

8 minutes ago, Altecice said:

I am suspecting that its the GPU and not your PSU. 

 

8 minutes ago, MVPernula said:

You have an older motherboard, it might cause the problem.

It most likely doesn't serve enough juice through the PCI-e slot.

 

And it might be a bad GPU.

But how the GPU worked fine with a 450watt power supply.and how does a GPU fail overnight? I switched to the other PSU did not work and then to the old PSU again and it still did not work

I don't think it is the PSU but what about the motherboard?also how can a 750w PSU deliver less power thought the pcie than a 450watt PSU