Remaining likely suspects are CPU, motherboard and power supply.
Your graphics card won't wake up until the MB BIOS passes control to it after some power on self tests (POSTs).
Are you hearing any system beeps? Do they differ from the usual?
If so, check the MB and BIOS manufacturers' websites for info about what they mean. This may help you to distinguish between MB and CPU problems. If you've never heard a beep, even when it was working, check that your system speaker is connected to the MB. If there isn't one, or you suspect the one you have, borrow one from an old system or plug a pair of headphones into your sound card output.
The power supply is a definite possibility. If you can hear your HDD spin up, and you can open and close your CD tray, then the basic +5V and +12V supplies are OK. That leaves +3.3V, +5VSB (standby) and the ATX +12V which runs the CPU voltage regulators on the MB. Also the PWR_OK or PG (power good) signal which is at 0V when the system is off, then usually rises to near +5V when the PSU is up and running. It must reach at least +2.4V. Until that happens the CPU stays in reset and won't do anything. To check every voltage, you could get hold of a basic multimeter. Most hardware stores stock cheap ones. The meter probes can be pushed into the back of the PSU connectors on the MB to make the checks. Black probe to 0V or the system chassis, red probe to the voltage you're checking.
Standard wire colours are black 0V (same as the system ground and the reference point for the others), red +5V, yellow +12V, orange +3.3V, purple +5VSB and gray PWR_ON. Blue -12V and white -5V may also be present, but are little used these days.
Check every wire. If you see anything wrong, note the spec. from the PSU label and replace it with the same or better.
Please!! don't be tempted to try fixing a dud PSU yourself; they contain lethal voltages. In fact, don't persist with a flaky PSU anyway, they have been known to fry other system components.
Sorry about the word count; I hope this is useful. |
