Question My pc restart after 30 seconds without monitor signal

Aug 2, 2019
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hello !
i've tried 3 differents mb's and 5 ram's sticks and 3 different cpu's but nothing is working
specs
cpu : i5 2500
gpu : GTX 960 (inplugged)
mb : i've tried this 3 mb's : h61m-p20 (G3) / h61m-p30(G3)/h61m-k
ram : 5 sticks of different mhz / 1333mhz / 1600mhz
psu : chinese 750w but it works and the psu fan is working
hdd : inpluged

please help guys i've tried all the possible ways
 

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