PC Boot Problem

Got an few year old E-machines that I am trying to fix for my brother and am having some problems getting it running.
Worked as a tech for awhile so I'm not TOTALLY ignorant and here is what I have tried and what the problem is.

Turn on the PC, fan runs, CD-ROM light stays on...no beeps, no nothing no display etc. After much research I went ahead and took out the battery to reset the CMOS - turned the PC on and voila, it came on but it had long beeps...until I realized the RAM was out. Put some RAM in (DDR1) and turned it BACK on. The PC booted up fine with a little grinding sound from time to time, possibly the PSU going out (?). Realized the PS2 keyboard and mouse weren't plugged in, powered it down with the button on the front, retried with them both plugged in, and its back to nothing happening except the fan running. I'm fixing to pull my hair out.

My first conclusion would be that either the Power Supply is going out / turning the PC off when it was finally up and running messed it up again so I may need to reset the CMOS again? I just don't know if a bad PSU would cause this from happening or not...going to try and run a PSU tester on it externally and see and maybe it'll show some results? Not sure though, that's why I'm here.

I have checked different video cards and swapped the memory in and out different slots etc as well so we can eliminate that.

Any help would be awesome...thanks guys!

Dylan