Question --Retro Memory Issue-- Half Ram, not your typical case

[yago.cascallar]

Hello Everyone.
I must apologize in advance for my english because it is not my native language, let's see if I can express myself correctly. I am currently building a retro-gamer (with whatever I find ) and windows 98. Here are the specs:
Intel Pentium III Katmai Slot 1 500Mhz
MoBo VIA Apollo Pro rev 22 VT82C596
Ati Rage LT Pro AGP 2x
And the memory, oh boy the memory:
Slot 1: Unbranded SDRAM 512Mb PC 133
Slot 2: Sometimes, yes, sometimes recognized as Kingston SDRAM PC 133 256MB, and (I know it sounds extremely strange) some other times seen as 512 DDR2 PC2-2100 133 (32MX64PC133CL3168) No shit.
Slot 3: Kingston SDRAM PC133 512Mb
(64MX64PC133CL3168).
So here is the riddle, depending on the slot they are, Windows and MoBo recognize different amounts. In case you're wondering yes I'm aware of Windows 98 and memory limitation, and I think I've fixed whatever limit was marked.
But I only get 512Mb.
Looking documentation as far as I could, I found out that this motherboard admits up to 1Gb of Ram and there is another variant, not so sure that goes up to 1,5 Gb, but nope, It always says 512 or less.
I thought about being some sort of bios config limit so I left only one sitck and gues what, I only get half the amount of RAM no matter what stick I get.
Let's say I drop 1 sitck, I'll get 256 recognized by windows. 2 sticks? If one of them is the multi-soul one I'll get anywhere from 384 to 512. 3 sticks? 512 no matter what.
CPU-z recognizes each slot and shows full amount, but windows and mobo don't. Crazy story, folks.
Any clue?
Thanks in advance!

 

[Calvin7]

Back then when deciding on memory to use, buying memory that was manufactured at the same time was recommended.

Using different modules is the least desirable configuration. You can use three of the same thing on motherboards as old as the one you have for best compatibility. A 512MB PC133 DIMM goes for about $20.