To see if it can work with your computer hardware you need to:
- Look which interface the graphical card uses.
- See how much power it needs.
The most used interfaces on a regular PC are:
- ISA ( 8 bits) (1984-ish)
- ISA (16 bits)
- EISA, MCA, VLB
- PCI-e (Roughly since 2003)
I said regular PC since non-PC style hardware will use other connections. E.g. Suns and mbus.
Almost graphical card for a PC which you can currently buy will use PCI-e.
PCI-e comes in a few flavours:
First of all there is the version. PCI-e v1, v2 and v3. These are compatible. No need to worry about it.
Second of all if the number of lanes. Usually denoted as x1, x4, x8 and x16.
Almost all graphical cards come in the x16 form factor.
So briefly: Look at the motherboard you have (or at its manual). Check if you have a free PCI-e connector. Check how large it is. Look at the graphical card you want to buy. See if its form factor matches or is smaller.
(A x4 graphical card will work fine in a x1, x4, x8 and in a x16 slot).
The next step is to check how much power the card uses. Does it need extra power connectors. Which (the 6-pins or the 8-pins version). What does your PSU supply?
So much for the hardware side: The remaining question is: "are there drivers for my card?". You might not find a driver for a new card and an old OS (e.g. no drivers for current cards and OS/2 or NT4). And vice versa, if you are buying an old, possibly second hand card: Is there a driver for a modern OS?