More than just "run hot", they were the "passive" models that require external cooling. You might be interested in these 3D printed designs for the cooling:

http://www.thingiverse.com/thing:997213

http://ssrb.github.io/hpc/2015/04/17/cooling-down-the-xeon-p...

As you mention, you'd still need a motherboard with 64-bit Base Address Register support, but at least you could keep it from burning up (or more likely, shutting down when it overheats).