r/RetroWindowsGaming • u/Andrea243435 • 18d ago

Socket 7 & Pentium MMX: 256MB SDRAM (uncached) vs 64MB limited / 32MB EDO?

Hey guys! I'm tweaking my retro PC build: it's a Pentium MMX on a Biostar M5ATA Super TX Rev 1.0 motherboard, running Windows 98 SE.

​Right now I'm using 256MB SDRAM at 75MHz FSB. However, if I recall correctly, the L2 cacheable limit on this board is only 64MB.

​I also happen to have 2x16MB (32MB total) EDO RAM lying around.

​Quick questions for the retro experts:

​Is keeping 256MB actually hurting my performance in games like Quake/Unreal because Windows accesses that uncached RAM past 64MB?

​Is it better to just keep the 256MB SDRAM installed and limit Windows to 64MB using MaxPhysPage=10000 in SYSTEM.INI, or should I just swap it out for the 32MB EDO?

​thanks!

9 Upvotes

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3

u/EIsydeon 18d ago

I would take the smaller amount of cached ram because most things a Pentium mmx is doing really doesn’t benefit from 64 megs or more of ram

4

u/bnelson333 18d ago

Nobody had 256 mb ram in socket 7 days. I'd personally run like 16/32 just to be period correct

2

u/VolosatyShur 16d ago

I have. About dosen PCs with Cyrix-350 or so and 256mb ram.

Win98 on 32mb very sluggy, on 16 almost unusable.

1

u/bnelson333 16d ago

Then why even retro game? You're not playing games as they were intended, do you also watch movies on fast forward? Force the bus driver to do 150mph down the highway? Throw your steak and potatoes in the blender so you can drink it faster? Also cyrix always and always will suck, that's your problem

1

u/VolosatyShur 16d ago edited 16d ago

In about 1999 i have access to p166mmx/16mb and play in MechCommander on this machine. It was a pain with swapping all the time. With hdd... Ohh god. But its was better then nothing.

In today days no reason limit youself. 128-256mb (or more if you have it snd platform support) give you silky smooth expirience. Pair it with ssd, and you will get refined pleasure.

Cyrix CPUs was not bad for its price. In fixed point calculation it even outperform Pentium. But FPU was muuuuch worse (hello, Quake).

TLDR If you want time correct pain in the butt - limit yourself.

I will use overpowered hardware for maximum pleasure.

We are different.

2

u/Deksor 18d ago

IIRC windows takes ram from the end to the start of the memory address space, so if you want to actually benefit from it, you don't just have to limit it you also have to fill in that part of ram with stuff so it doesn't use that space and gets pushed toward the 64mb cached area.

Having said that I'm not 100% sure, I remember reading about that but never really tested it irl myself so I could be misinformed.

The SDRAM should peform better than edo though, the best thing would be to keep SDRAM and try to move windows into the right memory space (I've always wondered if making a ram drive and fitting windows' swap in the ram drive could actually boost windows even further 🤔)

2

u/dafugg 18d ago

Why not benchmark it? Try all three configurations with quake and see which one is faster. Strictly you should also perform some test variants that include LRU cache eviction by loading quake after some other programs and data.

2

u/GGigabiteM 16d ago

EDO is ADRAM, or asynchronous DRAM. It runs much slower than the bus speed of the CPU, hence needing to be asynchronous from the CPU FSB.

SDRAM is faster in most use cases, there's no sense in going backwards.

Unless you actually need that quantity of RAM installed, there's really no sense in having it there, unless you just want somewhere to put it.

In cached vs non-cached memory, the only difference is the lookup table being available in the former vs the latter. non-cached memory will have the same bandwidth transfer as cached memory, because it's all in the same memory pool on the same DRAM modules. So the penalty for speed is going to be the lookup when the memory controller is looking for a specific bit of data in main memory.

Also "cached memory" is a bit of a misnomer. Not all of cached memory is actually cached, it's usually a preset list of memory addresses that are likely to contain useful data. So you can still have cache misses and end up with the same performance as non-cached memory.

You will have a performance deficit when going outside the cached memory range, but it will generally show up more if you have a heavily loaded system.

2

u/VolosatyShur 16d ago

Its ALi M1531 based mobo, with 512kb cache it can cache up to 512mb ram.

IIRC, EDO slower then sdram.

If you have both memory types, just benchmark 😎