It should work with matching pairs (2 x 1 Gb, 2 x 512 Mb in the right slots), according to http://www.crucial.com/store/listparts.aspx?model=Pavilion%20a1700n. If it doesn't, call HP or read through http://forums.cnet.com/5208-6122_102-0.html?hhTest=1&forumID=44&threadID=301021&messageID=2810767
And what's in your fathers PC now?
Here's the problem I'm having. First off, I've changed RAM before, added, taken it out, everything, but I've never had a problem like this before so hopefully someone can shed some light on the subject. I have an HP Pavilion A1700N desktop, but with an added video card, and added RAM memory. I had it running on the 2 x 512mb chips it came with, and I purchased another 2 x 512mb set to go with it, and it was running with 2.0gb perfectly. My dad has a newer HP pc, and since the RAM in each computer was identical, (Both PC2-4200), he had 2 x 1gb sticks, so I figure, okay, 2 x 1gb + 2 x 512mb = 3gb. However the computer refuses to operate this way. It will not accept all four in at one time. It will only work with three. I've alternated banks in every possible combination, but it will only work with three. In some instances, with four in, the computer will re-start itself over and over again, or lock up while loading Windows Vista. I removed one of the original chips that I had left in there, leaving it with 3, and the computer booted up, and indicated that it had 2.5gb of memory. I put the chip back in the spot and removed the other chip, and it worked just the same, but when I put that chip back in, it started playing its games with me again by not booting up correctly. Am I missing something about mixing two different capacities of RAM in different slots? Is there a reason this is happening? Obviously the slots in the motherboard are working, and the chips are working too, but for some reason, it just doesn't work all-together.