Computer does not pass POST/does not boot and no display

Hi there,

I bought my desktop PC from PC Specialist in February 2015, so I have not even had it a year. These are the specs:

Processor (CPU) Intel® Core™i7 Quad Core Processor i7-4790 (3.6GHz) 8MB Cache
Graphics Card (GPU) Asus Nvidia GeForce GTX 750 ti
Motherboard ASUS® H81-Gamer: ATX, LG1150, USB 3.0, SATA 6GBs
Memory (RAM) 8GB KINGSTON DUAL-DDR3 1600MHz (1 x 2GB)
1st Hard Disk 500GB 3.5" SATA-III 6GB/s HDD 7200RPM 16MB CACHE

Everything was working fine for, well I suppose the first 6 months or so. Then I started having problems. The fan would get very noisy quite often, however this did not seem to affect PC performance, just raising the noise levels. Then, a couple of days ago, the PC shut down after maybe several hours of being on. It would then attempt to reboot, and stayed on for about 3 seconds before shutting off. About 3 seconds later it would then try rebooting, however 3 seconds later it shut off again and this would continue. I solved this problem (as it now turns out, not permanently) by re-seating the CMOS battery, and that seemed to work. However last night, after perhaps a day of being on, it shut down again. And now when I try to start it, it starts but does not boot past the POST test, and there is no beep to tell me this. However, all the fans are running and LED lights on both the motherboard and GPU are lit. It just does not boot and no display is shown on my monitors. After doing some extensive reading online, in which I identified a number of possible causes, this is what I have done so far to try and troubleshoot the problem.

With the AC cord removed, I have removed and reinserted the 20 (or 24)-pin main power supply connector to the motherboard. This made no difference.
I have disconnected the blue USB cord and the cords to the hard drives and powered on the PC. This made no difference.
I have removed my RAM and re-seated it in the same slot on my motherboard. This did not work.
I have removed my RAM and re-seated it in a different slot on my motherboard. This also did not work.
I removed my RAM entirely and powered on the PC. There was a three-tone beep (one long beep then two quick beeps). This is my motherboard telling me that the RAM is missing. I am therefore quite sure that my motherboard is still fully functional and is not the issue.
I have removed my PCI card (GPU) from the motherboard and instead connected my monitor cables to the slots on the motherboard. This also made no difference. I am therefore also quite sure that my GPU is not the issue.
I have also tried re-seating my CMOS battery again, and this did not work.

I have deduced that it could be my RAM, or my CMOS (unlikely since CMOS batteries should always last longer than a year), however my strongest bet is that my Corsair 450W PSU is the issue. It spins when the PC starts however it appears to only produce enough power to light the LED's and not boot the computer. Over the lifetime of my PC the PSU has been getting very noisy and I am now not sure if I should have picked a 450W power supply as it may not be strong enough to support the PC and its specs' power demand after all. I am a hardcore PC gamer, and I play a lot of demanding Steam games such as Arma, DayZ and Euro Truck Simulator 2, so it is likely my PSU has been straining a lot and has now finally conked out. Can anyone confirm if my PSU is the likely culprit, and also if I should have gone, and should now go for a more powerful PSU in the first place? Thanks.

P.S. I have a 3 year PC Specialist warranty on my PC however I only have one month left until the 'parts' aspect of my warranty runs out. I have not removed the PSU or tampered with it in any way yet so my warranty is still intact. What does 'parts' on my warranty mean? Thanks

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(NT) Start a warranty claim.
- Collapse -
Trying that again

Start a warranty claim.
Ask the maker what a parts warranty is.

Clean the filters.
Get a can of compressed air and give the innards a good cleaning.
Don't forget the psu give it a few shots from both directions.
Get a new cmos battery their only a few bucks.

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