I should have of course mentioned that this is a DELL XPS 420 tower - sorry.

The motherboard has a sticker labelled CN-0TP406-70821-7C6-IOUU Rev A01 on the major component (eg. RAM sockets) side of the board.
The motherboard also has P63117C 94V0 R02-015 written using the etching process on the underside.
The motherboard also has 316764300018 TF-PCB,TED-DPN,PWA-SAN MARINO/MB,SILVER.R02_A01.12*10.5.T=1.6MM,6LAYER silscreened on the underside.

The short is evident across the ATX 4-pin 12V connector on the [major component side] of the board.
The capacitor...

Am trying to repair my desktop motherboard that suddenly wont boot.
I noticed that a surface mount capacitor has blown and also there is now a short between +12V rail to GND.
Any help is appreciated.