I got a new computer and assembled it myself. I've done assembling before also. This time though when powering up there was nothing on the screen but all the fans are rolling. The setup is as follows
ASRock Z68 Pro3
Intel i5 2500K@3,3 Ghz + Mugen 3 cooler
Asus HD 6870
2 x 4Gb Kingston RAM
Nexus NX-5000 PSU, 500W
Crucial 64 Gb SSD with Ubuntu installed
tested with 2 different screens with dvi, vga and display unit
After checking everything and trying to power it several times I got it into the boot screen a couple of times. The funny thing seems to be this never happens when I have my keyboard is attached. Even when it isn't most of the time I get a blank screen.
Therefore I started testing different components. The graphics card works fine in my old setup so it shouldn't be the part causing problems. The PSU is from my old setup so I thought I should get a new one in any case so I bought a Corsair CX500 PSU. The same problem persisted. I also tested the new PSU with my old setup and it is ok.
I also saw a link on this site to help troubleshooting. I tried booting with every component off excep the CPU and I got the correct error beeps. After attaching RAM I didn't get any sound and the guide suggested that the RAM might be shorting the PSU.
Therefore I went to my friend to test the RAM and it didn't work in his setup either. He got a blank screen too. I borrowed his Excelram 2 GB comb but I even that didn't solve the case. Once again I managed to get into the boot screen and this time I took a picture:
I tried plugging in my keyboard but the computer wouldn't accept any input. After a few more startup tries I saw a spark in the motherboard and after it there was a smell of something burned in the air. Here is a picture of the component(s) where I saw the spark:
After all my tests I would think the problem is somewhere in the motherboard. Atleast after the shortcut. I would like to hear someone else's opinion too before buying a new motherboard though. If any more info is required or if I missed something I'm pleased to offer more details if it helps solve the case.
More about :blank screen random boot screen success
Now after experimenting more with my friend's RAM I managed to get into BIOS. There everything seems to be ok. The CPU and M/B temperatures are 30-40 degrees celcius and the voltages are what they should be. The problem is still that the operating system won't load. I see the hard drive in BIOS but when it starts to load the OS it just stops showing anything on the screen. Another thing is that even now it won't boot every time even though it is more frequent than before.