[SOLVED] pc keeps resetting in loop

[Spoc40]

Hi I built my first pc a few weeks ago and yesterday after exiting the bios menu it shut down and restarted then shutdown and restarted and doesn't stop restarting. If it manages to stay on splash screen it does a beep then a few seconds later it beeps again until it reset again. Also some times the cpu fan doesn't even start and occasionally sounds like something shorting I have tryed a different psu and checked all ram sticks un plugged fans even tried with no hdd tried a different cpu took the gpu and pci wireless card out and even stripped and rebuilt and also took out cmos battery . The parts are all second hand and comprising of.
Gigabyte Z77 ds3h mobo
I5 2500k
Asus ac51 wireless pci card
16gb corsair vengence blue
Gigabyte geforce gtx 660 gpu
Old Cooler master air cpu cooler
Corsair cx550w psu
Old seagate barracuda 500gb hdd
Cit blaze pc case

I'm wondering if the mobo is faulty or if the connection from the case to the mobo is shorting any ideas or thoughts on this would be much appreciated

 

[Spoc40]

Hi I built my first pc a few weeks ago and yesterday after exiting the bios menu it shut down and restarted then shutdown and restarted and doesn't stop restarting. If it manages to stay on splash screen it does a beep then a few seconds later it beeps again until it reset again. Also some times the cpu fan doesn't even start and occasionally sounds like something shorting I have tryed a different psu and checked all ram sticks un plugged fans even tried with no hdd tried a different cpu took the gpu and pci wireless card out and even stripped and rebuilt and also took out cmos battery . The parts are all second hand and comprising of.
Gigabyte Z77 ds3h mobo
I5 2500k
Asus ac51 wireless pci card
16gb corsair vengence blue
Gigabyte geforce gtx 660 gpu
Old Cooler master air cpu cooler
Corsair cx550w psu
Old seagate barracuda 500gb hdd
Cit blaze pc case

I'm wondering if the mobo is faulty or if the connection from the case to the mobo is shorting any ideas or thoughts on this would be much appreciated

SOLVED after striping and rebuilding again to no avail I sor a post about the backup bios so I held power and reset for 10 sec and switched it on to find it was now a long beep n 3 short beeps now saying my gpu was bad so took out gpu turned bk on to find I now had a corrupt main bios? And it automatically started to fix it self so after tht I put gpu Bk on and yay Same again so took it off repaired bios and now have running pc but no gpu but least it's working. I have had a thought could the cmos battery be failing il replace ASAP incase