Q: How much memory can I put in Mac Pro 2009/10.

If you mean a mid-2009 MacBook Pro, 8GB.

If you mean a mid-2010 MacBook Pro, 16GB if it has a Core 2 Duo CPU and 8GB if it has an i5 or i7 CPU.

If you mean a Mac Pro, 48GB for a four or six core model and 128GB for one with eight or twelve cores.

(144081)

As suggested by Neil, you need to be much more specific about the exact Mac you are dealing with.

Is it 2009 or 2010? It cannot be both.

Is it a Desktop Tower Mac Pro or a Laptop MacBook Pro?

As you see the answer changes dramatically depending on what exactly it is.

You can find out here:

https://eshop.macsales.com/MyOWC/