no screen on hd 5850

[longcoming]

I have a Vtx hd 5850,foxconn a76gmv mobo,4 gb 1333 mhz ram,500 watt high power psu.

There is no screen nowadays when ı use vtx gpu.when ı somewhat push the gpu on motherboard,there is screen.when ı leave it,screen goes away.
I used another gpu,hd 5450 on this mobo.no issues.
I used vtx on another two legacy mobos,no screen whatever you do.

I cant decide ıf ıt is gpu,mobo or the power supply.
Thanks already.

 

[longcoming]

I tested the gpu on a local computer repair shop on another mobo.It works flawlessly.
I tested the power supply,no problem.
İt is mobo.
Damn foxconn,how bad motherboards they are producing.