What is the best GPU, etc my old school Lenovo can upgrade to? Here are my Specs:

DirkDiggler10000

Commendable
Jul 17, 2016
7
0
1,510
What is the best GPU my old school Lenovo can upgrade to? In summary I have a 4gb ram Lenovo core 2 duo with integrated Q45/G43 graphics that I am really trying to upgrade to its full potential (as a project). Yes I know there are better computers out there but I'm really trying to find out how far I can upgrade this specific computer (or 4 of them actually; I got a good deal from a friend) PLEASE give me some suggestions for how to improve this computer (I've already upgraded the RAM from 2 to 4gb and upgraded to a 2tb HDD). I'm basically turning them into media players and for GoPro picture sorting/edits since I have tons of pics.

Here's the specs: (wish I knew how to post pics of my Speccy screenshots but I'm new to these forums sorry in advance)

Motherboard:
Lenovo LGA 775, Intel chipset Q45/Q43
Southbridge 82801JB
Bios: Lenovo 5CKT77AUS
PCI Data:
PCI Slot 1, "slot usage available", Bus Width 32 bit;
PCI Slot 2, "slot usage available" 32bit;
PCI-E x16 (data lanes x16) "slot usage: unknown",
PCI-E x1 (data lanes x1) "slot usage: unknown"

CPU:
Intel Core 2 Duo E7300 @ 2.66GHz
(I also have 2 of the same computers with E7500 @ 2.93GHz)

RAM: total slots 4; used slots 2; free slots 2
DDR3 Dual Channel
Number of SPD Modules: 2 (slot 1 & 2)
 
Solution
Technically, you can put a GTX 1080 if there is a powerful enough PSU and no space restrictions.
But practically, anything beyond GTX 750ti would be kinda overkill