You may have a bad ram stick causing the board to stop while checking ram. I would try each ram stick one at a time to see if they work. Some have a lifetime warranty, or oem can range from ninety days to one year. You can also try removing or replacing the board battery. This resets the bios. Do this with the system off.
Your system is hanging up on post (power on self test).
Since it wont let you into bios, it's probably not the old Keyboard not found, hit any key to continue.
You checked the ram. that's good. Now you need to check the drives, one at a time.
That would include hard drive cd/dvd drives and any old floppies/usb t\drives etc.
Just disconnect the drive, and try to get to bios.
If it's not the drives, check any add in cards you have, like nic, modem (ya some people do still use phone modems), sound card, etc. Just pull them out, and try to get to bios.
BTW if you just added a second drive to an existing pata cable, you may have forgotten to designate one as slave, the other as master.
Please remember to turn power off, before disconnecting, pulling anything. I use the power switch on the back of the psu, as that keeps the system grounded.
Sounds like it could be the motherboard to me. I had a similar problem with an ASUS P5N-T Deluxe. My motherboard wouldn't get past the BIOS splash screen (Press DEL to enter BIOS/TAB to view BIOS post message) and I had to RMA it. Try all the above solutions, but you might have a bad mobo.
Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.
Make sure you plug the CPU power cable in. The system will not boot without it.
I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.
You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.
If no beeps: Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.
At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.
The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.
A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.
This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.
If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.
Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.
Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST. At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.
Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
My system is working now, i dont know how it started again, just removed all the connections for hard drive, then i was able to acceess setup menu. then again reconnected the hard drive. This time the system started. so not sure what caused system to start. But thanks everyone for their inputs...