Yes, the "turbo cache" cards do not physically have the full amount of memory on them. They share system memory to achieve the full 512 meg. These cards were made for OEM systems. Did the card come in a retail box with all the bells and whistles, or did it come like an OEM card, plain box simply wrapped in an anti-static bag? It likely came out of an HP Media Center PC. They are the standard cards in those systems, and a lot of people replace them with something better because, well, quite frankly they are not very fast cards.