I have a HP xw6200 Workstation, that is rather long in the tooth, and with 2 physical CPUs, it is quite inefficient. So, the plan was to upgrade the internals.

Nothing special:

• AMD Athlon II X4 640
• ASUS M4A78KT-M LE (mATX)
• 2x 2GB DDR3 1333MHz RAM.
  3p under my £150 budget

The issues:
The pin connector for the front panel isn't a good fit, but I can trim it to size.

The PSU has a 8-Pin Power connector, unsurprisingly, the new board has a 4 pin socket. The pins do line up, but I would have to cut it in half to fit.

Finally, due to the weight of heat-sinks, they are screwed directly into the case. It turns out that these screws also lock the motherboard in place. As to remove it, you remove the heat-sinks, slide the motherboard across and lift it out.

I tested the new board for fit, and while it slots in fine, it's not secure. There is nowhere to screw the board down, it is just held in place with plastic standoffs. The only idea I had, was to wedging something between the side of the motherboard and part of the case.

Any suggestions?