My computer did not boot after I put it to sleep, I was not even able to get for the bios. I turned it off at the wall and left for about 10 minutes but it made little difference. I tried this a few times. I then cleared the RTC ram using the jumper on the motherboard. I unplugged the computer, placed the jumper in the clear position, left it there for a minute, put it back in the normal position and pugged the power cable back in. When I turned my computer on a black screen appeared with a white curser flashing at the top right. I left it for 20 minutes and nothing happened. I turned the pc off, left it a while and tried again and nothing appeared on the screen at all. The computer did not beep. All the fans come on and the motherboard power LED is also on.
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:
Check for line power at the PSU input. Extension cords, power strips, and power cords do fail.
If you have power and no beeps, suspect components in likely order are PSU, motherboard, and CPU.
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 green wire will alway have 5 volts on it. When you press the power switch, the voltage should drop to 0 volts.
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. If you get this with motherboard graphics, your motherboard is bad.
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. In this case, you will POST successfully (single short beep). But your monitor will display a "missing signal" message.
In that case, the first thing you do is to test the monitor and data cable with another system to make sure it works. If the monitor works, the video card is bad. If you have motherboard graphics, again, the motherboard is bad.
I now know that it is the CPU that is the problem. I have decided that I will get a new motherboard and CPU (and probably PSU). I am not sure however if I need to deactivate windows so that I can reactivate it with the new motherboard. I am planning on formatting the hard drive. Will I also have to deactivate other software such as Microsoft Office. I have windows 7 professional 64 bit upgrade version. Will the fact that its upgrade edition be a problem? If it makes any difference I still have windows XP on a disc with the CD key.