Well, I started having a problem where my computer constantly reboots and has no video when I switched computer cases. I'm guessing i short circuited something, but not sure what. I had to let my sister's friend figure it out. He just took everything apart, and put it back together again. He put in another video card to reset everything. About a week later, my computer started to randomly freeze when I started to play games so I decided to try to take out the video card/ RAM and put them in again after dusting everything which my sister's friend instructed me to do. Now when I turn it on, it sounds like my CD-Drive is stuck, and my computer sounds like it's constantly rebooting. There is no video either. I tried replacing my 4670 with my old 2600XT to see if I got video. Didn't get nothing. Was thinking of replacing the Video Card/Mobo... Oh, and also my power LED on my computer case keeps flashing which probably tells me my computer is constantly restarting. The hard drive makes a weird sound which seems to sound like its running but also sounds like my computer is rebooting. Can't really explain it. I hope someone can shed some light on this problem..
The breadboarding thread has a paragraph about how to build and test a PC in stages.
Breadboard with just motherboard, CPU & HSF, case speaker, and PSU. You do have a case speaker installed, right? If not, you really, really need one. If your case or motherboard didn't come with a system speaker, you can buy one here: http://www.cwc-group.com/casp.html
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.
At this point, you can sort of check the PSU. Try to borrow a known good PSU. 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.
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.
Install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card. Silence or long single beeps indicate a problem with the memory.
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.
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.