What is the process of stacking a new processor chip on top of an old one called?

Piggybacking. But why would you want to do that???

Piggyback upgrades are performed by stacking a new processor on top of the old one so I suppose it is called piggy backing. Directuins on how to do it can be found at

www.smartcomputing.com

Years ago, you could buy a CPU accellerator to make your computer faster. It worked by putting the chip on top of the processor, but beyond that I'm not sure how it did what it did. In this age of technology, putting one processor on top of another will end up with one not working and the other overheating. Bad idea.

stacking a new processor chip on top of an old one

they used to have some old overdrive processors that worked like that, a long time ago, the theory behind duo core processor is similar, but they are built that way, you can't add on to the one you already have, other than that, I never heard of it

Pointless.

not a Mac