Hey there! Long story short: Me and my brother tried to remove an graphics card (Geforce 260 gtx) but then realized the "retainer clip was gone". Im guessing that it had been broken off or something. Yes we removed all the screws. The card is only stuck near the end. I guess one solution is to use brute force but thats not a risk we are willing to take hehe So yeh im hoping someone can help us out here Cheeeeeeeeeeeeeeers!
Should just be a little piece of plastic, they are a pain in the neck, but it's at the front side of the slot not toward the back, they vary greatly, look your specific motherboard up, hopefully covered in a PDF file of the manual.
Find something to push the plastic part out of the way of the card notch so the clip moves, I find an smallish hex wrench works well, although you'd want to use a plastic piece if you hands are not steady.