A very nice guide, but nothing that I already didn't know. Also it's from 2006, and that's pretty clear after reading things like "There is also a lot of nonsense written about RAM requirements, for example one site said 512MB is adequate for a Windows XP system if you only run one application at a time or if it's your grandmother's computer - I'm guessing the author doesn't own a PC but instead owns a Gaming Rig". What does that say about me, when I'm trying to put 3GB on a Windows XP system? Since I got no explanation for the "double-sided 16-bit" expression, I'm going to buy the 4x1GB DDR3200 Low Density from ebay (twice) and try them out on both motherboards. If they're not compatible, I got a few old desktops laying around that also need DDR memory, if for some reason they're also not compatible with those then I'll re-sell them online locally.
Yep, as stated in the linked manuals in the 1st post. I'll try the 4x1GB from ebay, the only downside is that they take about 3 to 4 weeks to arrive, so I'll only have a concrete answer 1 month from now. Arrgggh! The HP board will only need 2x1GB because it's running XP and it already has 2x512MB. The Asrock board is intended for 4x1GB and is waiting for a new CPU to arrive, but it doesn't have CMPXCHG16b, so it's a no-go for Windows 10 64-bit. It's an Athlon 64 x2 4400+ 2.2Ghz (ADV4400DAA5CD) for socket 939, and only newer CPUs for socket AM2 started having this feature. I read somewhere that if installed from DVD, Windows 10 x64 it will not check for this feature, so when it arrives I'll try a clean install of Windows 10 x64 from DVD. Even if it works, there's no way of knowing if/when the CMPXCHG16b feature will actually be needed.
Reminds me of an old gigabyte board I bought brand new around 1999 or 2000. The manual said it supported a max of 4 GB, but 8 GB worked fine after a BIOS upgrade. GA-8ITXR I think it was.