it appears we haven't even reached the point in the computers boot process where the hard drive comes into play.
computer boot process is like so (sort of):
1 power goes to board.... bios microcode performs power on self test (post)
2 POST....bios microcode checks for things it needs to run.... ram,CPU and a display device. if they not found, play a long distressing beep.
3 if ok, it kicks the CPU to start and the CPU reads code from BIOS rom and performs each action in turn... this....
4 CPU initilizes video device
5 CPU tests ram (if enabled)
6 CPU plays "beep" to confirm the POST completed without error. if there is an error, try to beep some kind of error message (short and long beeps)
7 CPU runs more BIOS code to configure the system to get ready for boot. (harddrives, ports, ram speed settings, other bios settings) and configures the motherboard accordingly.
8 hard drive initialised and ready for data read/write
9 CPU loads boot stuff from selected boot device (as configured).
10 stuff starts to load, programs run, operating system does things.
by the sounds of things, you are getting stuck somewhere in 3, 4, 5 but not so far as 6. your board is kind of working becasue you can jump it on with the power switch jumper (so low level computer stuff is running)... but not so far along as completing the POST (power on self test) where it plays the beep (signifying POST is complete and ready to boot.) and not far enough that the CPU is able to put out it's own beep error code.
this makes me believe you still have a ram issue. since we have eliminated the videocard and you say the cpu is "new"...but the computer still behaves the same as the old one... i'd say ram.
really if all you swapped from the old system is videocard and ram and you tested the videocard and it works... process of elimination says ram to me.