Carlos S. M. wrote:

Intel 945 series chipsets doesn't memory remap support all, >=4 gb will be always seen as ~3.5 GB, i did get a 945 board post (Dell Dimension 9150) with 4x 2 GB RAM, Dell BIOS could see all 8 gb, but all OSes even Windows x64 and linux x86-64 only detected 3.5 gb ram, tried XP x64, 7 x64 and 10 x64 and ubuntu 18.04 lts 64 bit, Windows 7+ sees as "8 GB (3.5 GB usable)"

indeed I have a gigabyte 945GC board that even supports the latest 45nm C2Ds and OC to fsb 333 but it still has the limitation of not having the remap feature and you can't access 4GB even on win x64, I think their first budget chipset with this feature is G31.

Seems I have in my stock a P4RD1-MX. It only has two DDR-1 slots, so not sure about the remap feature on that board. What tests would be useful to test its (relative) performance?

Not much is found on the web on that particular mainboard.

AsRock P4Dual-915GL has an AGP ("fake" AGI version) slot.