Computer on but no image on montor

DCFC79

Ok im stumped on this, ive got a computer which was actually working the last time i used it and now there is no image on the monitor when the desktop is on. The monitors actually work as ive tested them on another desktop. What could be the likely cause ? I have noticed it doesn't beep when turned on. I havent tried unplugging all the plugs on the board and RAM and made sure they are inserted correctly but ill try it later. Apart from starting from scratch what else could i try ?

Appreciate any advice/pointers given

Thanks

fwor

If it's definitely running Ok and not locked up, there is the possibility that the graphics card/chipset has failed.

But the most common situation I've seen is where the PC was last used with a CRT monitor, and then a similar LCD screen is swapped in. A CRT can generally handle a higher refresh rate than an LCD, and when out of range, some will just not come on or display anything.

DCFC79

fwor wrote: »

If it's definitely running Ok and not locked up, there is the possibility that the graphics card/chipset has failed.

But the most common situation I've seen is where the PC was last used with a CRT monitor, and then a similar LCD screen is swapped in. A CRT can generally handle a higher refresh rate than an LCD, and when out of range, some will just not come on or display anything.

ok theres no cards attached the mb, its been used with an lcd for months plus the last time i saw it working was on an lcd screen. Ill strip it down and just try 1 stick of RAM with just the hard drive connected and ill see what happens. I took the case off and i had a listen to the cpu fan and the fan sounded like it slowed down then sped up again then slowed down and would repeat it again and again so is that a clue as to the problem or just me, ill try various things and post back tomorrow

thanks fwor

Lil306

Following on from above posts....

Disconnect all hardware and use onboard VGA (if it has it), only the processor should be connected, see if it posts first.

If you don't even see the post screen you either have a faulty PSU, faulty CPU, faulty M/B OR possibly a duffed BIOS

If you don't get the POST screen with components disconnected...

1 - Try swapping a known working Power Supply if possible...
2 - Disconnect and reconnect the CPU power connecter (4-pin) incase it's iffy
3 - Try resetting the BIOS, that might do the trick of someone has played with your settings

cit_k

also
Check nothing has fallen on the board causing a short.
Check nothing has fallen under the board causing a short.
Ensure all socketed chips are in firmly, ensure memory is in firmly.

DCFC79

Ok Ive just got it working or so I think I have. I removed 1 stick of RAM and removed the psu and put in another psu and its now working. I did notice on the psu i took out that some of the pins in the plugs that you use for fans etc weren't inserted correctly so i might try the other psu again or maybe the psu i removed was of 350 wattage and the 1 i have inserted is 500w

Lil306

DCFC79 wrote: »

Ok Ive just got it working or so I think I have. I removed 1 stick of RAM and removed the psu and put in another psu and its now working. I did notice on the psu i took out that some of the pins in the plugs that you use for fans etc weren't inserted correctly so i might try the other psu again or maybe the psu i removed was of 350 wattage and the 1 i have inserted is 500w

A cheap tool you can invest in is a Thermaltake PSU Tester, it will test you PSU in seconds and tell you if it's faulty

Cost me about £5 for mine on Fleabay, nice cheap tool for a PC toolkit

http://cgi.ebay.co.uk/ThermalTake-A2358-Dr-Power-PSU-Tester-20-24-Pin-Sata_W0QQitemZ310158659279QQcmdZViewItemQQptZUK_Computing_PowerSupplies_EH?hash=item4836e58ecf

The only really important fan to hook up is the fan ontop of the CPU Heatsink, it is a square 4-pin

If that is duffed the CPU effectively has no cooling and what happens with processors

- Intel (detects no cooling, shuts down automatically to prevent overheat)
- AMD (catches fire in worse case scenario)

I actually did this when I bought a motherboard upgrade kit, thought nothing of connecting the 4-pin plug, blank screen was visible thought the board was duff. Googled it and after connecting 4pin it worked fine..

Also as cit_k says a shorted motherboard can give similar occurences to this