Alpha R2, stopped booting

Hi Everyone!

Woke up this morning to my Alpha R2 very dead. Working fine yesterday, no sign of life this morning - won't boot, no fan activity, nada. As I turned the system over to read the service tag, heard something metallic sliding around inside. Not a good sign. As the thing is so out of warranty, went ahead and opened the chassis. Inside, found two small springs and a plastic post floating around. I found the source of the parts - they held down the metallic square (cooling block?) circled on the picture. Unfortunately, the metallic square lifted off easily and the coolant glue was no longer doing it's job.

Couple of questions for the hive-mindWhat's under the circled metal cooler?:

• Anyone know what the chip under the metallic square is? It's not the CPU or GPU though it's pretty big in terms of real estate on the motherboard.
• Any suggestion what else I can do to see if the problem is small or large? I'm guessing the motherboard would be replacement part if I wanted to resurrect the system - is that a correct assumption?
• If it is the motherboard that needs replacing, is it worth even trying to repair? Looks like a replacement is around £400 plus a lot of building to move CPU, GPU, RAM, etc. over to the new motherboard.
• Anything else I should think about in the situation?

Thanks in advance for your help! John