No Start up

[Blyths]

Hi guys,

I have been having a lot of trouble with my computer just restarting for no reason, and then recently the Mach11 cools to -33 and nothing happens? like no power getting to the motherboard!

It just goes to about -45, and shuts down.

I removed the motherboard, and when I took off the back plate behind the cpu, the electrodes were covered in white & greenish colours, so I presume thats means "dead" motherboard.

So I replaced the motherboard and re-used the CPU from the old one, which had no dis-colouring at all and looked fine, but after re-building, as soon the Mach11 gets to -33, nothing happens and it shuts down! again likw theres no power getting to the motherboard?

Does this point to the Cpu? I did think at first power? but all the motherboard power Leds lights are on!

thanks

 

[stocky]

This can happen when the Molex from the MachII isn't connected/ not connected properly to a PSU molex. Check that just incase and report back

 

[Blyths]

It all seems connected correctly, you dont think Cpu then?

 

[stocky]

If I remember right, the system should still power even without a CPU in the socket. I think it's more likely to be the PSU at this point.

You can check the PSU by shorting the sense wire to earth. The sense wire (only green wire) is on the main motherboard connector. unplug the main motherboard connector and use a small piece of wire between this and any earth (black) wire (a black one next to it!). The fan should spin on the PSU and anything else still attached should fire up if the PSU is okay...

 

[Blyths]

Ok thanks stocky, I will give that a try!

 

[Blyths]

Did that Stocky, and the psu worked ok, even the fans and dvd drive started.

So I presume must be the main power connection molex from the mach11 to the motherboard?

( I have checked the molex connection and that seems ok)

If you agree, can you remember how you built it and what I should look for?

thanks

 

[stocky]

I think that there is a connection to the control board. I'll have a look through my archive and see if I can find any more info/ pics...

 

[stocky]

I found a pic which shows the main Molex connection on the control board - it appears to be using an extension cable to the PSU molex connector. Both of the connection points have a red circle around them:

 

[Blyths]

Thanks stocky, I will have a look tonight and let you know

 

[Blyths]

I have checked all the connections and cannot see any loose wires, I tried changing the power molex from the mach11 board to the motherboard but still no joy,

I turn on the PSu, the MB power leds light up, the Mach display is on, I press the power button, the Mach11 cools down to -33 then nothing, no power goes to the mb to start it up!

So it leads me to think it could by the Mach11 controll board?

Any ideas?

Thanks

 

[stocky]

Okay - check the LED's on the control board and see if there is anything unusual. There is another connection which goes to the on/off header pins on the motherboard from the control board. I believe that it is a white and blue wire. check this throughout, as thinking about it this is probably the most likely cause as a signal isn't getting to the mobo from the mach!

 

[Blyths]

Theres 4 leds under the control board, when mach11 is plugged in A Green light is on which flashes.

When front power button is pressed and Mach is activated, 1st yellow light comes on, when temp reaches -33 2nd yellow light comes on, then since no start up, mach turns off and both yellow lights go out. I think the last light is a red one.

Thanks I will check this white/blue wire.

Oh Bol****s, that could be it thinking about it, if its on the wrong way round?

I never even though that could cause this problem! I will turn it round tonight and let you know.

Many thanks

 

[stocky]

I don't think the polarity matters as it's an open/close circuit. However, it is more likely to be a contact issue, so check both ends are well connected. It wasn't soldered longer was it? If it was check the solder joints...

 

[Blyths]

Right, the white & blue wire only went from the main on/off switch to the control board, the only connections on the motherboard header was the Power LED, HDD LED, and the Reset switch.

After alot of searching and following wires, I deceided to try the Reset switch on the Power SW header, and IT WORKED!! ( Nearly )

(Its amazing how something so little can cause so much stress!)

Now at -33 the motherboard starts up, Dvd drives light up, case and Gpu fans spin but nothing else, the monitor stays blank.

Does this now point to the Cpu?

Thanks again for your help

 

[stocky]

Nice one

I think it points more to the memory (-esp because it's a SLI-DR!) or video card. I think it tells you when there is a CPU error or if one isn't present...

Look at the LED's on the motherboard, as they are great when fault finding

 

[Blyths]

Wells its not the CPU! As I have just changed it and thats not changed a thing.

-33 , all powers up, but no monitor. It seems no signal is going to it! I have tried the graphics cards in SLi and single but no joy - i dont think its these anyway.

I have changed my motherboard as my Dfi got damaged, am trying to use a abit kn8-sli to keep me going to i upgrade in march.

I will try one stick of mem at a time to see if that works.

Thanks for your help.

 

[Blyths]

Tried one stick at a time and still nothing, and also tested my monitor cable on another system and thats ok.

I havent a clue now, what to try next

 

[stocky]

The motherboard seems to be suspicious...

 

[Blyths]

I agree, am thinking about taking it back to Maplin ( yes dont laugh, I was desperate ) and changing it.

(Just hope I can get all the seal string off)

I think a Asus will be ok? any suggestions ( Its just until march so around £100 is my max I think)

 

[stocky]

I think that the DFI SLI-DR was generally the agreed 'best board' for the skt939, although I'm sure folks with newer 939 boards could argue otherwise...

I can't recommend another board as I haven't used others for that socket type!