Need some help to troubleshoot a problem and fix it

[tareqghaith8]

Hello I've seen that many people came here for help and they found it so I'm trying my luck with this.

My problem is that my pc boots but no display on my monitor but it's not the typical one I have an hdd light that doesn't work when this normally happens but this time it's different the light works and the sound of booting up seems normal to me, I recently Installed a new motherboard and a new cpu so I need help figuring out the cause of the problem so I can fix it I installed a DH87RL mobo with a pentium g3220(only for testing)
I have a PSU of 400w and I think the PSU is the cause of the problem but I need confirmation that it's the cause.

Sorry for my bad English and thanks in advance.


Note:sometimes the pc shuts down after booting up and also there's a green light on the mobo that blinks steadily when I boot the pc up,
Also I'm a new timer here so I might have forgotten to add some notes.

 

[rustech]

Hdd led shouldn’t be always on. Right after you press the button it shouldn’t show any activity at all.
Anyway, try all different variants of plugging your monitor to integrated GPU: hdmi, dvi-d, displayport. You don’t have a discrete GPU, right?
Tell us exact models of your components and monitor, please.
Check if all power connectors are plugged tightly. Unplug them and plug back. I mean motherboard’s 24pin and cpu’s 4pin connectors. Also try to put memory stick to another slot.

 

[tareqghaith8]

If u mean by discrete gpu an external then yes I have a GTX650 1GB Ver
And I tested all my memory sticks and they are working properly they are (4x1) and (2x2) they are all with the speed of 1333 a total of 8gb
I'm sure everything is plugged properly and I tried the integrated graphics and it didn't work either also tried a different gpu a gt710 to be exact and also it didn't work.
Also I tried on 2 monitors and none of them worked also all of my components are tested on another pc except for the PSU.