Rebuilt PC will not start.

[wightrob]

I have read a few threads on this subject and they all seem to point to the PSU.  However it seems unlikely, although not impossible in my case.  Here's the scenario.

I started off by upgrading some components and ended up replacing everything but the case, HDD and DVD drives.

I have used the following components:
PSU - Blue Storm 500w
Motherboard - Elitegroup 755-A2
CPU - AMD Sempron 3000
RAM - Kingston DDR SDRAM 512Mb
Graphics Card - nVIDIA GeForce 6

I connected all the power leads and case leads as instructed to the motherboard, as well as power leads to the components. There is no real indication of which way round some of the small plugs go (i.e. Power, Reset, Sleep) so I don't know if it is important.

With the mains power lead connected I switched on the PCU power switch which illuminates showing power. When I press the case power, nothing happens at all.

As the case is old, the case fan is powered from a standard power connector rather than the dedicated socket on the motherboard. It occurs to me that there may be a saftey feature to stop the PC firing up without a case fan, I cannot find any help on this in the motherboard manual or website.

Any comments will be appreciated.

[ale52]

Disconnect everything power & data cabling (hard drive, floppy drive, cdrom drive) excepyt the video card & RAM (even the connectors to the mb for the hdd, reset, etc. EXCEPT your power connector).  Try to start now.  Post back

Alan <><  

[wightrob]

Thanks Ale52,

I did just that,  firstly with the main and auxillary mainboard connecters in place.
The result was, as before, no activity.
Then I removed the auxilary plug, this time the CPU fan started.
I tried it again with the case fan connected to a standard line.
Both fans ran.
I tried reconnecting the aux plug, just in case it had not been seated correctly but there was still no activity.
I didn't try reconnecting the drives but I assume that all the power is there now.
I am curious about the aux power supply to the mainboard.
What is it for?  Do I need it?  My old mainboard does not have one.

Rob

[GX1_Man]

Keep in mind that because you have some power, it does not mean that you are getting correct power. Assuming the build is correct (and I'm not) that would point to the PSU.

"There is no real indication of which way round some of the small plugs go (i.e. Power, Reset, Sleep) so I don't know if it is important. "

[wightrob]

Hey, I'm not really as stupid as this quote makes me sound.  :-/

So, what is the deal with the 4-pin mainboard plug?  My old mainboard only had a 20-pin connector and my old PSU does not have a 4-pin plug.  I have been told that the 4-way plug powers the CPU.  Is this correct?
I checked a new Dell PC at work today (with the permission of the systems guy) and there is only a 20-way supply and mainboard socket.

[wightrob]

OK folks, it has been sorted.  I received postings on another forum indicating that I may have used the wrong 4-way connector to the motherboard.  This turned out to be the case.  The Blue Storm manual which is in black and white only shows the 4-pin motherboard connector on the same loom as the 20-way connector.  The correct one is in fact the separate 4-pin plug with 2 yellow , 2 black wires.
Thanks for all the positve comments.
Rob