Fans work /no post - black screen

By sickster
Sep 20, 2007
  1. Firstly my front usb's stopped working for a day, no other problems at all b4 this.

    Then i was away for a few days (computer off) on return computer would not boot. no beeps. no post, just fans and black screen.

    I tested the two ram modules and both have some led lights, i tried taking one out/ then swapping them etc no difference.

    I thought then it was the mobo, i replaced it w a (untested) secondhand mobo.
    This time fans start for a moment then stop, still no post no/black screen etc.

    I tested the power supply in another mobo/old sys and it powered up and there was post sound.

    I have now found that the fans work when the 4pin atx12v is not plugged into the board. as this powers the chip i am wondering if the chip is fried or if it may be something else?
  2. sickster

    sickster TS Rookie Topic Starter

    more info:

    I have also replaced the power supply with 600w jeantech

    also i have since tried to disconnect all power to all but the mobo and 4pin atx 12v - still same problem

    i have removed all the pci cards and graphics card - still no joy

    So what do i have left to do? disconnect any other drives completely and check for poss shorting of mobo?

    The cpu and ram have been reseated when i replaced the original mobo

    any help much appreciated

    why do fans work when atx 4pin is not connected but not when it is connected?

    obviously the system will not post w this disconnected but why do the fans run?

  3. Tedster

    Tedster Techspot old timer..... Posts: 6,000   +15

    have you tested your ram?
  4. edddder

    edddder TS Rookie

    pls check also your video card is properly inserted (if you are using one)
Topic Status:
Not open for further replies.

Similar Topics

Create an account or login to comment

You need to be a member in order to leave a comment
TechSpot Members
Login or sign up for free,
it takes about 30 seconds.
You may also...

Get complete access to the TechSpot community. Join thousands of technology enthusiasts that contribute and share knowledge in our forum. Get a private inbox, upload your own photo gallery and more.