Custom Build Problem [HELP]

Hi guys, im new around here and my english is not that good. But anyway lets get into the problem shall we?

i made a custom built PC here at Overclockers back in Jun 2015 and the parts are:

->Asus Radeon R9 290X DirectCU II 4096MB GDDR5 PCI-Express Graphics Card (R9290X-DC2-4GD5)
->Intel Core i5-4670K 3.40GHz (Haswell) Socket LGA1150 Processor - Retail
->MSI Z97 Gaming 5 Intel Z97 (Socket 1150) DDR3 ATX Motherboard
->EVGA SuperNova G2 750W '80 Plus Gold' Modular Power Supply
->Cooler Master HAF 912 Advanced Windowed Midi Tower Case - Black
->Western Digital Caviar Black 1TB SATA 6Gbs 64MB Cache - OEM (WD1003FZEX) HDD
->Noctua NH-U12P SE2 Dual Fan Quiet CPU Cooler
->Kingston HyperX Fury Black 8GB (2x4GB) DDR3 PC3-12800C10 1600MHz Dual Channel Kit (HX316C10FBK28)
->LG 24x DVD±RW SATA ReWriter (Black) - OEM GH24NSC0.AUAA15B

Ok so this was the build and boy it was running fine and smooth until one night i turned it off, and the other day when i went to turn it on it wouldn't, it was stuck on a 2-3 seconds reboot loop. I opened the case and took off the rams, change sockets, reset bios everything you can imagine, and still nothing, i put it sideways on a chair turned back on with one ram and it was working again. ok turned off put it back on the same place, and keep using it with only one ram. then again i turned it off one day and the same problem, i assumed it was the rams so i bought new ones, this time they where:

->Corsair Vengeance Low Profile 8GB (2x4GB) DDR3 PC3-12800C11 1600MHz Dual Channel Memory Kit (CML8GX3M2B1600C11)

Put back on the PC and still nothing, the same 2-3 seconds restart over and over again, then i thought it was the MoBo so i bought a new one

->MSI Z97 PC Mate Intel Z97 (Socket 1150) DDR3 ATX Motherboard

I put everything together turned it on with the new rams, and nothing, i kept trying until i smelled something burning, i couldn't see what it was but from the smell it was one of the rams. I started changing rams from slot to slot and i manage to get it stable, it doesn't restart every 3 seconds but its just on, doesn't show anything on screen its just like there is nothing plugged to the screen. Having the same problem i thought i must be something else so i bought a new CPU just to test it.

->Intel Pentium G3260 3.30GHz (Haswell) Socket LGA1150 Processor - Retail

Turned everything on and still the same problem it turns on, doesn't show anything in the screen and as far as i can tell its not booting its just on, i don't know what else i can do i also tried with a different Power Supply but it was less powerful. Anyway this has been going during for 8 months as i don't grow money on trees, i tried going to a technician and its as good as i had burned 60£. So bottom line is, I got it to not restart every 3 seconds but he just stays there on and doing nothing, no image no beep, if i change ram slots the restart every 3 seconds comes back, its like the only one that doesn't make it restart is the 3 slot counting from the left to the right.

Sorry for the long long thread, i tried to explain it exactly how it happened so you guys can have a idea of what its going on.

Please if someone had this problem and solved it or any solutions please let me know, i really appreciate some help at the moment as i think i done everything i could imagine.

Thanks in advance,
Regards

The first thing to do is take it all out of the case and connect motherboard, ram and cpu to the power supply and try again. If it works like that we can probably troubleshoot from there.

yesterday i got a spare RAM and i test it again, with all out of the case again, an guess what it worked fine, put everything back together inside the box turned it on and again nothing, took everything out and try it again outside the box again and it wasn't working anymore.. sincerely i don't know what more i can do with this.

Works outside the case and not in the case. I'd say it sounds like something is shorting in the case

i noticed that when i start the pc, the fan on the power supply doesn't even turn.. it keeps the pc on without doing anything but the fan doesn't turn, and when it was on the 2-3 seconds restart loop the fan would turn almost half way stop then go again then stop.. like it was stuck or didn't had enough power to keep turning.. in this note i'm guessing its the power supply but at the same time i'm not sure if its normal or not that the fan doesn't turn. any suggestions?

Thanks guys for trying to help