Mac Pro randomly turns itself off (again)

every time it shuts down, i hear a click from the PSU (similar to the click sound when you press the power button at the front starting up). When trying to switch it back on after it dies, the power button sometimes wont power it on right away. i had to wait at least 10-15 secs for it to work. when it does work it sometimes will shut down with that click only 2-5 secs after pressing the power button. it sometimes dies right after the chime. it also boots through without any problem.

A few times when i happen to stare at the LED on the front of the back board (in front of the PCI fan) when it dies, i see the top two LEDS flash once as i hear that click, the ones which are highlighted red in the picture (not a picture of my actual Mac). it also sometimes flashes when i press the power button but wont boot up after it dies. Please, what does this mean?

THank you... nothing in the LED cluster glows even when AC cord is pluged in. im currently boosting my PCI, Intake and exhaust fans to around 2000-2500 rpm using Macs Fan Control. Do you suggest i boost the other fans too? (PSU, CPUA, CPUB fans are set auto).

How can i know for sure if it is overdrawing the power supply and what can i do?

BTW i play quite a lot of games so i mostly use bootcamp. thanks again

Here's a video showing a new problem which ive never encountered before.... The moment i press the power button i hear a sound and it wont boot whatsoever (the creeking sound is audible in the video)

*sigh*** God knows for some reason i cant upload the video..... this is depressing.... dont ever use a mac!!!! It will ruin your dreams, carrier, morale and your life.... help!!!!!

sorry, will try to upload the video....thanks for the reply, really i would have given up long ang if wasn't for all you good people trying to help out appreciate it much!... Its getting really depressing

couldnt upload the video here but here's is the link: https://www.youtube.com/watch?v=VOt23UxRh9o

Note: please crank up the volume so you can hear the creek sound clearly the moment it dies.

Funny thing is i can now boot, use the Mac after a few moments but im pretty sure its gonna die on me again after some time. here's a pic of the current Mac fan control settings im using at the time of the last shut down. (btw it also dies even if i dont boost any of the fans)

Thank you lllaas, ive been suspecting the PSU but wasn't sure, is there a way to diagnose the PSU and be absolutely certain? There are no apple service centres in my area and no other mac hardware to test with. I Can order it but I want to be sure, not waste my money this time and move past this problem.

in the video, the first sound is the click as i press the power button (0:03 secs), then the unusual sound follows almost instantly as the light on the GPU goes out (0:04 secs). ever crank the ignition key of your car mistakenly while the engine is already running? its very similar to that sound.

After months of waiting i managed to get my hands on a new PSU which costs a little more than twice the price of a normal PSU (because its Apple?).

installed the new PSU but while doing so i dropped a small tool between the processor bay and the cabinet so i had to remove the processor bay to get it out. Put it all back together, i noticed some RAM leds were lot ao i remove those RAMS. But after a little while (about 3 mins) after booting up the fans cranked up to max speeds... This happens everytime. The fans will start running very high a short while after powering on. Help please.

Thank you for the quick reply, you've really helped me a lot Illaass. Found out what seems to be the cause. Pulled the processor tray out, found a pin broken in the socket which the processor tray connects to the Main board...... could this be the issue?

Checking Macs Fan Control, the current RPM of BoostA and BoostB reads 0 (zero in orange color) when the fans get sped up. BTW i am using a single video card Strix GTX 980ti with a separate external power supply