I don't even know what a inside is... so okay!
>v>
And yeah. You said you wanna change a PC GPU(Graphics Processing Unit), so I'll give you a guided tour of mine. I'll do the pictures after I've had my tea. I'll point out things of use and knowledge, give some advice I picked up, and tell you what the difference between PCI-E and AGP is, in case your PC uses AGP. It probably won't, but better safe than sorry.