I've been given an old(ish) graphics card, with the make and model not listed clearly, or at all, on the card. Or perhaps they are, but are covered by the heatsink. Assume also that I don't have access to a machine to play with, into which I could check whether the card fits.
How can I tell, by only looking at the card itself and without trying to insert it anywhere, whether it's a PCIe card or an AGP one? I remember the physical slot interface is somewhat similar with both of them having an L-shaped latch towards the back, which makes it relatively easy to mistake them with each other (as opposed to PCI cards which don't have this latch).