Greetings. About one month ago my pc suddenly started having trouble booting. I'll number the symptoms for easy reference.
1) When I wanted to boot it if I clicked the power on button it would flash the lights for half second and then stop and nothing happens.
2) In order to boot it I had to turn the PSU off for a little and then turn it on and leave it on for about 10 mins before I click the on button and then it started booting (the time that I had to wait after the on/off of the PSU before powering it on increased gradually).
3) About 2 weeks ago, I started noticing that after I turned it on it would start the fans and the lights but there would be nothing on the screen, eventually after about 10 to 30 seconds the bios would start and it would boot normally.
4) Occasionally (became more frequent gradually) 2 seconds after shutting down completely it would power up by itself without anything appearing on the screen (like 3.). Most of the times after about 10 seconds it would stop and shut down for good but some times it would just stay at this state until I turn it off.
5) This might be unrelated but I had blue screen twice during this month and I can't even remember the last time I had one before that. I took a pic of it the second time with my phone (I assume both bsod were the same but I could be wrong) and it says driver_irql_not_less_or_equal.
6) This one might be unrelated too but from time to time since I can remember during boot the logo of the Bios and the BLANK prompt of cmd style with the underscore _ would appear all distorted and MOVING vertical lines would appear but it would stop when windows started booting (no I am not doing drugs, but I can't say the same for my pc).

Even though I don't think it has anything to do with it I should mention that the Hard Drive that the Windows are installed in is a bit messed up (hanging from a thread) but I had it like that for years and I only realized when I opened it (the guys putting it together put wrong cable, anyway).

2 days ago pc turned itself off while I was using it and I couldn't get it to boot like I used to. I replaced the CMOS battery but to no avail it seems. Today I got it to boot after leaving it for hours in each state of on/off PSU wise, but after reconfiguring the bios to default (because of the new CMOS battery) it got stuck at that blank prompt like thing right after BIOS with the flashing underscore(it was blinking normally but nothing else happened) and after restarting from the button same thing happened every time. I reseated some cables and the RAMs and I'll try again tomorrow.

From what I have gathered it's probably the Motherboard. I just need someone with more experience to advice me.

CPU: Intel Core i7-950 Processor (8M Cache, 3.06 GHz, 4.80 GT/s Intel QPI)
Motherboard: Asrock x58 Extreme (s1366/DDR3)
RAM: Corsair XMS3 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600
GPU: Sapphire HD 6870 1GB GDDR5
HDD: SEAGATE Barracuda SATA II 750GB 32MB 7200.12No, the most probable  answer is Power SUPPLY.
What is the name of the power supply and its wattage?
All or most of those symptoms come from failing Power Supply.
Also, anything that draws too much power  might do that. Such as a RAM stick that is defective. Or a  DVD/CD drive. Or the graphics card.



PSU: Nexus 1000w rx-1k silent modular

Edited first post and added it there tooPromoted an other information to numbered symptom because I can now reliably reproduce it.

7) When I boot it after leaving it for hours in each state of on/off PSU wise it gets stucked at that blank prompt like thing, right after BIOS, with the flashing underscore (it is blinking normally but nothing else happens).Update

I unplugged everything except fans, motherboard CPU and one RAM and the PC was able to power up normally without having to on/off the PSU. I then plugged the GPU and even though it powered up there was no signal on the screen (probably couldn't get to BIOS). I tested a second GPU and same results, except that once, with the new GPU, the symptom with No1 happened.It turned out to be the PSU (or at least that's what the tech guy in the shop said after doing some tests ). Thanks Geek-9pm for your insight.