Unless you can push your cache settings in the BIOS to a point where it becomes unstable there isn't anything to be gained by fitting faster SRAM chips.

List of CPUs you might actually need 15ns cache for at factory settings.
DX50
That's it, and it may run on good 20ns if there aren't any timing delays between cache and CPU.

BitWrangler wrote on 2021-06-09, 19:05:

List of CPUs you might actually need 15ns cache for at factory settings.
DX50
That's it, and it may run on good 20ns if there aren't any timing delays between cache and CPU.

Okay, so you are saying I can benchmark the cache and by changing the timing delay in bios to Zero I can
Check for improvements.
If nothing significantly improves then there is no need to upgrade cache ?

No. That's not what is being said.

If you can tighten your cache timings *without* instability then you don't need faster chips.

If better timings introduce instability, then faster parts may help, but the difference in performance between timings is likely to be marginal.

No. If you can push the cache timings to fastest and it's stable than you don't need faster chips. If it's not stable it might be with faster chips, but there is no guarantee it will actually be stable or work fine even with faster cache.

With faster timings there is always improvement.

Got it. Thanks guys.

So going from “0” to “1” wait state for dram only improved CPU performance by 0.1 percent
How does this look ?
Do you think I need a cache upgrade ?

0 is usually faster.

When changing DRAM/Memory timings, you need to test the memory speed. When changing cache timings you need to test the cache speed. Or test the overall system performance with 3Dbench and/or similar benchmarks.

For memory and cache benchmark I'd recommend SPEEDSYS.

For 33MHz BUS speed you don't need anything faster then 20ns. Even 25ns should be just fine.

The bios I have has no adjustable cache timing setting.
So I assume I am stuck with the default cache timing setting.

That's highly unlikely - can you post BIOS setup screenshots?

BioS screen shots:

I this is "DRAM Wait State Selection" option

BigDaddyM wrote on 2021-06-09, 21:18:

I this is "DRAM Wait State Selection" option

No, that's wait states for main memory. Which should be 0 if the system is stable at that setting.

Theres no cache tuning options on that page; only enable/disable.

Therefore the OP can't tweak the speed and therefore he'll get no advantage of faster SRAM chips.

What is a good program for benchmarking main memory ( ram ) ?

Super PI 32M 😉

Intel486dx33 wrote on 2021-06-09, 23:13:

What is a good program for benchmarking main memory ( ram ) ?

Like already said:

For memory and cache benchmark I'd recommend SPEEDSYS.

Get it here:
https://www.philscomputerlab.com/dos-benchmark-pack.html

Okay, DRAM set at “0” wait state was working at first. It played video CD movies better too.
Video play back was smooth with no hesitation.

And then I reboot the computer and it crashed on boot up.
It kept crashing so I had to change the wait state back to “1” in order to get it to boot okay.
But at wait state “1” video CD movies playback is a little choppy.

So there is definitely a Cache problem.
Not sure if the cache just needs to be re-seat or replaced.
But I will replace with 15ns cache anyway.

Its just that taking this computer apart is a pain.

With DRAM settings you only change DRAM timings - at least this is the understanding and cache timings don't change . Like said, at 33MHz 20ns is plenty fast.

If you have any other memory modules, try swapping them. Maybe they will work at 0-wait states DRAM.

I am using -60ns FPM ram now.
Maybe I will try to re-seat first because like I said “it was working at first”
I may have mismatched ram. I will have to check.