The most common issues I encounter and this is with the rather limited story given are:
1. The owner didn't plug in the ATX12V connection or the power connection to the video card (remember that no machine details are given so these may not exist.)
2. The owner installed ALL the motherboard standoffs in the new case and they didn't know to only install as many as required. The motherboard shorts out to the case and if they are lucky, removing the extra post brings it back but no warranty is ever offered and in fact as a shop owner you would write a note on the ticket stating the find and voiding any future or present warranty on the work and machine.
Bob
I bought a new PSU and case for my brothers computer, installed them, and the monitor wouldnt come out of sleep mode. All of the fans are running (CPU, graphics card, case fan) and the HDD is working as well. I tried plugging in another monitor and it didnt work either. I put the old PSU back in, nothing, and then the previous graphics card to no avail. What did I mess up/break along the way? Any help or troubleshooting steps would be greatly appreciated.

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