I do not know of any resources to get schematics for motherboards. Part of the reason is that they are just too complex and expensive to repair versus the cost of a new or used motherboard.
CAUTION: Use an ESD wrist strap and ground yourself before trying the following:
Remove RAM modules. Clean both sockets and edge connectors on RAM with 90 percent isopropal alcohol. Followed by drying off with canned AIR.
Do the same for the CPU and ALL plug in cards.
Tracking down an intermittent connection on a motherboard would be VERY difficult even with a complete schematic.
The problems are:
The motherboard itself is a multi-layer board. Many of the connections are buried inside the circuit board.
Some of the ICs on the board may be ball grid arrays.
These ICs have the connections soldered underneath the IC.
To repair a bad solder connection, you need to:
Remove the IC using special equipment,
Clean the circuit board and the IC,
Place a new array of solder balls,
Use special equipment to flow the solder.
Figure around $5000 US for the equipment.
Other ICs are fine pitch flat pack or "J" leaded devices.
Again, you need special soldering equipment to solder the leads without damaging the IC, or creating solder shorts.
If you are intent on trouble-shooting this board, your best option would be to get a POST card, and see if you can get a POST code that identifies where the boot sequence stops.
Figure on spending between $50 and $100 US for a POST card.
Chas
