On the early Intel 815 computers memory was limited to 512meg. This is a VIA setup so it is probably not limited. You have four memory banks and you have two chips in the first two. Every board will have a specification of the kind and the size for each bank. Clearly, if it has accepted the 512, it is recognizing it. On some boards in the past you had to balance the size so that you would have equal amount in each - in other words, if you had a 128 in one bank, there should be a 128 in another. Again, since your system is recognizing both memory chips, this does not seem to be a limitation for your board. Try the new BIOS first, then go from there.