2GB is plenty for XP games up to about 2007, and even 1GB is enough for games up to 2004.

Consult your motherboard manual to see supported memory speeds, because many AthlonXP or P4 boards would use lower memory speeds or slower timings if more than 2 sticks of RAM are installed.

I'd probably go with 2GB as 4GB and more seems more like Windows 7 territory to me.
Frankly, depending on what mobo and CPU the system is build around, 1GB and even 512MB will work fine until you start using software that outgrows the configuration.
If you (for whatever reason) want to use 512MB and something like a Pentium 3, stay with SP1 and perhaps SP2 at the most and use NLite or similar to slim down the install. Also tweaking the OS can make it run more snappy. I mean it will work but if you want easy mode with WinXP and performance just get something as recent as you can get away with.

So tldr: Get 2GB. 1GB will also work and you can use 512MB if you want to put it on a Pentium 3 or something.

My experience has been putting WinXP on systems like Pentium 3 1000MHz with 512MB SDRAM and a usual mechanical harddrive.
Later on I've installed XP on progressively faster systems, leaving the slower systems using WinME instead of XP.
Athlon XP and Northwood (especially >2GHz Northwoods) are basically WinXP territory and especially if you use lots of RAM and a relatively fast harddrive.

But it's really a matter of preference. WinXP will work on slower systems like Pentium 3, but it won't be as much as a speeddemon like if you put it on a Core2Duo with 4GB DDR3 or something.

RetroGamer4Ever wrote on 2022-05-08, 18:50:

I do 4GB for my XP builds. Even when paired with turtle memory, they are a beast with an SSD.

Similar here. My father and me expanded his Athlon 64 X2 PC in the late 2000s/early 2010s to 4GB RAM (4x 1GB I think) and added an SSD.
The PC just flew. 3,5GB RAM were accessible.
Windows 7 x64 was also installed on a secondary partition,
since it was the current OS at the time.
The main work was still done on XP, though.

Edit: More physical memory also helps a bit against memory fragmentation and memory leaks, I assume.
Windows XP still has an issue with a growing swapfile. Vista fixed this by default, I assume.

https://pcauthorities.com/windows/windows-xp/ … -xp-memory-use/

https://blog.techinline.com/2014/10/01/hotfix … ory-leak-issue/

TrashPanda wrote on 2022-05-08, 13:38:

Jo22 wrote on 2022-05-08, 13:31:

3GB

Edit: Or 4GB for dual-channel?

4gb is pretty pointless if running a 32bit OS, since you will only ever get 3.5gb of it due to how Windows maps out Video memory, 3 gb is pretty nice but 2gb will also work just as good for gaming.

Yea I know about the weird hacks that let you get 4+gb under a 32bit os but who the fuck wants to bother with that shit for a gaming rig.

Well with PAE Patching 4Gb+ could be used, but then all drivers need to be PAE aware.

(I use PAE on my i5 Notebook with 16Gb RAM)

pixel_workbench wrote on 2022-05-08, 20:04:

2GB is plenty for XP games up to about 2007, and even 1GB is enough for games up to 2004.

yes that's about right, and for those later games we can now choose to build a dual core 64 bit from around 2007-2010 and have 4gb plus average-good graphics card and windows 7, it will likely do it all just fine

XP on a 32 bit system is nice enough with 1gb generally

Wouldn't know about the performance question, but usually, for Windows itself, the more the merrier. As has been stated, 32bit will only ever use 3.5 GB.
20 Years ago, 1 GB seemed like quite a lot and should be fine for most things.
IIRC, the question changed a lot if you made the mistake to install SP3.

gerry wrote on 2022-05-09, 07:54:

XP on a 32 bit system is nice enough with 1gb generally

I know, it seems like 3/4GB are both overkill because they're so near on the edge on what's possible (to address).

On the other hand.. Decades ago, a typical CP/M 2.x system had 64KB installed - the maximum CP/M could handle without bankswitching.

If (if) we apply the same logic from XP to CP/M, then 16KB (1/4 the memory) must have been massive for CP/M.
However, it wasn't. 32KB, half the directly addressable memory, was barely enough to get things running - 48KB, maybe.
Those 48KB are like the 3GB on XP, if we apply that logic. 🙂

Lostdotfish wrote on 2022-05-08, 13:08:

I have no real experience of the later, PCI Express platforms.

Personally I'd go this way unless you don't want to go this way for nostalgic reason which is fair enough.
Hardware is cheaper and say a mid tier CPU is on par with a high end CPU from the previous generation without the price premium.

My XP build started off as a free parts build based off the Asus P5KPL-AM (Intel G31 chipset) but as I wanted to play around with SLI I upgraded to a Asus P5N (nForce 650i chipset) with a mediocre Xeon 2.50Ghz (pulled from dead server)
I've 4GB because I can, but I've never seen physical memory exceed 2GB, Running WMP, Speedfan, task manager on one screen and a later game on the other it can get above 1GB sometimes, but again thats because I can.
Really reto rigs rarely have more then 1 program (the game) running , it's not like back when they were the primary rig with internet crap and whatever else needed for daily driver duties.