P6823w

[Ballaimpalass]

Please Help! I am a beginner with computers, so I figured I would attempt to upgrade my old desktop. So I added 3 2x8 pc3-10600u 4gb sticks of ram. The first time I booted up my pc it worked just fine. Then I wanted to test another pc I had laying around with a similar alvorix rs880-uatx mobo, so I removed the ram from my first attempt and swapped them into my 2nd desktop to see which seemed faster. The 2nd pc had a slower processor so I went to return the ram to the first attempted hp p6823w and now, when I turn the pc on, the mobo has a green light (as always) the power supply starts along with fans and hdd. However my monitor stays in (sleep mode, no screen) and I have no beeps from the mobo speaker. After about 20 seconds or so you can hear the hdd slowing down almost like it's going to idle. Nothing else happens. I can't get into bios or anything. I've attempted to clear cmos and pwsd with no luck. Even when I put the original 1stick of 4gb pc3-10600u ram in dimm1, still no luck. Did I damage something? I appreciate any assistance! Thank you!

[Prométhée]

Hello
If I understood correctly ;
the computer worked!
you opened it, and placed a memory module, from another computer
it did not restart, you removed the new module, still the same problem, is that it?

have you taken the usual precautions (static electricity)
have you not touched elements with the memory module, or other ..
Little luck, but try this
unplug the computer from the power outlet, unplug all peripherals (printer screens, etc.)

remove the modules, make sure to keep the original one and not the new one, which you will then have to replace!
Long press the power button
replace the original module, then keyboard / mouse screen
restart
if the computer does not start the motherboard may be damaged