Lately my computer has experienced a problem whereby the monitor does not display anything despite the monitor being okay. my guess is that there is a problem with the system unit, can anyone tell me what's the problem?
is the power turned on?
LOL sry couldnt help that.
serious though, check the connections to make sure they are fully plugged in - ie not loose. That would be the power cable, and the video cable from the monitor to the back of the computer. I always make sure they are screwed in tight.
If its not a loose connection, other 3 possibilities I can think of are 1) video card overheating, 2) monitor is faulty, or 3) video cable itself is faulty. sometimes swapping out the vga/dvi cable might do the trick.
Do you notice that it happens after its been on for a while or could it happen when turning on the computer after its been powered off for several hours?
Does your monitor have different types of connections? (DVI/VGA/HDMI)? Which connection are the currently using? Can you try a different connection for a while to see if its related to the type of connection?
Work through our standard checklist and troubleshooting thread:
I mean work through, not just read over it.
Breadboard - that will eliminate any kind of case problem you might have.
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:
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:
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.
You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.
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 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. 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.