Gpu fans spins for 1-2 seconds then stops.

Hello guys 2 months ago i build a new system.Its only problem was that he wasnt shutting down.When i was trying to shut it down from windows,the screen was going black but fans kept running,so the only way to shut it down was from the psu's switch.
Two days ago i had the error "your pc ran into a problem and needs to restart'' many times,and i think i was getting that error because i wasnt turning off the computer properly.
Yesterday i tried to start it but nothing.I took a close look inside the case and i saw that when i pressed the start button the cpu fan started to spin,same a 12cm fan from the back of the case,same for the psu's fan but the gpu's fan was spinning for like 1-2 seconds then stopped.
Tried reseating the ram and gpu but nothing,same problem.I tried even to start it with the gpu's motherboard the screen stays black but the fans are running.Now my problem is that i dont know what is broken.Is the mobo or the gpu(i know for sure that the hdd is gone).I would say the mobo cuz it looks like the gpu wants to start but fails.Also when i start the pc without ram it doesnt make that beep beep sound that is warning me the ram isnt there.
The specs are:
Mobo:Foxconn A6VMX
GPU:ATI Radeon r7 240 1GB GDDR5 With boost
CPU:AMD Phenom x3 8600 (2.3 ghz)
4 gb ram(2x2gb 800 mhz) NOTHING OVERCLOCKED.
If you guys could help me with anything i would appreciate it.Also sorry for this bad english.

Hi
From your discription it could very well be the motherboard. If you have a mobo speaker and remove the ram and start it up and don't get a beep code telling you no ram installed points to a motherboard fault. It would be nice to know make and model of power supply and wattage

The PSU is a Raidamax RX-520 (520 Watts) 1 x 120 mm Fan
2 x SATA
1 x 20+4 Pin ATX
6 x Molex (4 pins)
1 x Floppy (4 pins)
1 x PCI-E (6 pins)
1 x 12V (4pins)

I would say the mobo is dead because it was faulty from the beggining by not shutting down with 3 different PSU's.I bought this one thinking ill fix the problem,but no.And by turning it off with the psu's switch i think i broke the hdd and mobo. But even if the mobo is dead shouldnt the gpu run normally?Also thanks for fast response!

Yeah if hard drive is removed still should get a picture on monitor.

Update...I took a Nvidia GF GT440 (2GB DDR3) to see if the gpu is faulty,but the monitor is still black so now i know the mobo is dead.Also i saw that when i press the start button nothing happens and after 5-10 secs the pc is trying to start(dont know how to describe this its hearing like two wires make a crack noise and its like its closing starting closing starting very fast and after making this stop start thing for like 4-5 times then it continues to run normaly) So the mobo is dead?If you need any more informations so you can help me ask and ill answer as soon as i can.

I would rma the board