Question Radeon hd7870 won't get recognised

[Lyadron]

My pc was working fine until yesterday. I disassembled my pc to clean it and after putting everything back together my GPU won't get recognised even tho it gets power (fans spinning). I have tried an older GPU I had and it's the same (fans spinning)(this one doesn't use PCI-e 6pins so it's gets power from the mobo). I have reseted CMOS. I have checked every cable connection twice. The only thing I can think of is maybe the PCI e slot on my mobo is faulty but the other GPU I tried was getting power (didn't get recognised tho) or my PSU is. Please help. My specs are:
Mobo : H61-M
CPU : Intl i3-2120
GPU : Sapphire Radeon HD7870 GHz edition
Ram : 2x ddr3 4gbs 1330 ghz
PSU : 550W
2nd GPU I tried : Radeon hd6570

Edit: my pc works fine with integrated graphics

 

[Satan-IR]

My pc was working fine until yesterday. I disassembled my pc to clean it and after putting everything back together my GPU won't get recognised even tho it gets power (fans spinning). I have tried an older GPU I had and it's the same (fans spinning)(this one doesn't use PCI-e 6pins so it's gets power from the mobo). I have reseted CMOS. I have checked every cable connection twice. The only thing I can think of is maybe the PCI e slot on my mobo is faulty but the other GPU I tried was getting power (didn't get recognised tho) or my PSU is. Please help. My specs are:
Mobo : H61-M
CPU : Intl i3-2120
GPU : Sapphire Radeon HD7870 GHz edition
Ram : 2x ddr3 4gbs 1330 ghz
PSU : 550W
2nd GPU I tried : Radeon hd6570

Edit: my pc works fine with integrated graphics

Considering it happened after cleaning and that PC works without the cards maybe there's some dust in the pcie slot that needs a blower to get out. I don't think that board has a second pcie slot.

 

[Lyadron]

Considering it happened after cleaning and that PC works without the cards maybe there's some dust in the pcie slot that needs a blower to get out. I don't think that board has a second pcie slot.

I've thought about that I have tried cleaning it even used compressed air and it still doesn't work
No it has only one unfortunately

 

[Satan-IR]

I've thought about that I have tried cleaning it even used compressed air and it still doesn't work
No it has only one unfortunately

If that doesn't work since you tried 2 graphics cards and none worked the culprit maybe the slot.

If you can try the 2 cards on a different working motherboard and they work that'd make the slot being faulty even more probable since as you said the motherboard works fine otherwise.