Common denominator is the PSU. Try a different known good PSU.

SodaSuccubus wrote on 2020-11-04, 17:18:

Regarding testing:

Try running a test program like GoldMemory or Memtest. Try with L2 cache disabled first to isolate the ram, and then with it on afterwards.

Thatl root out any ram induced problems. Bad cache in particular can manifest as verious anomalies.

I did passes with and without cache, RAM is fine.

I swapped in the p90 I had, everything seems to be working fine except NFSSE, but I'm pretty sure it just hates EMS. I'll try the PMMX233 again tomorrow when my new thermal paste arrives and if it still doesn't work, I'll contact the ebay seller and tell him it appears to be faulty.
EDIT: Nevermind, even without EMS Need for Speed still won't boot and locks up the whole machine.

cyclone3d wrote on 2020-11-04, 17:50:

Common denominator is the PSU. Try a different known good PSU.

Don't have another AT PSU that works at the moment.

What about an ATX PSU with an AT adapter? I don't really trust most AT PSUs anymore.

cyclone3d wrote on 2020-11-04, 19:13:

What about an ATX PSU with an AT adapter? I don't really trust most AT PSUs anymore.

This what I'd need?
https://www.amazon.com/20-Pin-Power-Supply-Ad … e/dp/B01EDGS0KI

tomexplodes wrote on 2020-11-04, 19:57:

cyclone3d wrote on 2020-11-04, 19:13:

What about an ATX PSU with an AT adapter? I don't really trust most AT PSUs anymore.

This what I'd need?
https://www.amazon.com/20-Pin-Power-Supply-Ad … e/dp/B01EDGS0KI

Yep, that will work.

If you don't mind waiting a while, you can get them on eBay from China for $3.25 a piece though.
https://www.ebay.com/itm/18AWG-20Pin-ATX-to-2 … 86/313021103999

There used to be a seller on eBay that sold the adapters that also had the -5v added (antronst) but he stopped selling them probably a year ago now. Not even finding that seller on eBay at all now.

rmay635703 wrote on 2020-11-03, 14:58:

Not all OLD boards actually use multipliers the same way. […]
Show full quote

Cyberdyne wrote on 2020-11-03, 09:43:

233MMX is a special case cpu, it reuses 1,5x speed as 3,5x in capable motherboards. But i have never heard that 1,5x speed will in turn change to 2,0x speed. This is new.

Not all OLD boards actually use multipliers the same way.

At one point in time board manufacturers could float or ground a multiplier pin (their choice) later on this wasn’t acceptable.

That is why many boards from the socket 5 era with the 2nd multiplier pin may not behave how you want.

Yes, that's almost without a doubt the issue here. A P55 CPU without internal 3.3V connection, and thus floating BF0, in an older mobo jumpered for 1.5x, will run at 2x. It can be kind of verified by jumpering for 3x multiplier, the CPU should end up running at 2.5x.

Here's an article describing the issue in detail better than I could ever do in a foreign language.

In short, the solution is to find 3.3V somewhere on the mobo and use that to pull BF0 high. A simple way to do that is to remove the CPU, put a piece of wire in one of the holes connected to the VCC3 plane, and start continuity testing to different unused headers/points on the mobo. If you find a header pin connected to the VCC3 plane, you can get away without any soldering on the mobo. Patch a suitable resistor in a dupont jumper wire or similar, use it to connect the CPU side of the BF0 header to the VCC3 pin, and you're good to go.

cyclone3d wrote on 2020-11-04, 20:26:

Yep, that will work. […]
Show full quote

tomexplodes wrote on 2020-11-04, 19:57:

cyclone3d wrote on 2020-11-04, 19:13:

What about an ATX PSU with an AT adapter? I don't really trust most AT PSUs anymore.

This what I'd need?
https://www.amazon.com/20-Pin-Power-Supply-Ad … e/dp/B01EDGS0KI

Yep, that will work.

If you don't mind waiting a while, you can get them on eBay from China for $3.25 a piece though.
https://www.ebay.com/itm/18AWG-20Pin-ATX-to-2 … 86/313021103999

There used to be a seller on eBay that sold the adapters that also had the -5v added (antronst) but he stopped selling them probably a year ago now. Not even finding that seller on eBay at all now.

One problem, which I realized too late. The only ones I can find (and the one I ordered https://www.amazon.com/7-Inch-20-Pin-Button-C … /dp/B075ZPWJBX/ ) only have 2 prongs for the power button. Both the cases I have have 4 prongs for the power button. Whoops. Need a new switch I guess? I can't quite figure out the right terminology to google a new one.

EDIT It occurs to me they may only NEED 2 to function. Thoughts?

kaputnik wrote on 2020-11-05, 08:56:

Yes, that's almost without a doubt the issue here. A P55 CPU without internal 3.3V connection, and thus floating BF0, in an older mobo jumpered for 1.5x, will run at 2x. It can be kind of verified by jumpering for 3x multiplier, the CPU should end up running at 2.5x.

Yup, that was the issue. I've since switched motherboards.

tomexplodes wrote on 2020-11-05, 20:46:

cyclone3d wrote on 2020-11-04, 20:26:

Yep, that will work. […]
Show full quote

tomexplodes wrote on 2020-11-04, 19:57:

This what I'd need?
https://www.amazon.com/20-Pin-Power-Supply-Ad … e/dp/B01EDGS0KI

Yep, that will work.

If you don't mind waiting a while, you can get them on eBay from China for $3.25 a piece though.
https://www.ebay.com/itm/18AWG-20Pin-ATX-to-2 … 86/313021103999

There used to be a seller on eBay that sold the adapters that also had the -5v added (antronst) but he stopped selling them probably a year ago now. Not even finding that seller on eBay at all now.

One problem, which I realized too late. The only ones I can find (and the one I ordered https://www.amazon.com/7-Inch-20-Pin-Button-C … /dp/B075ZPWJBX/ ) only have 2 prongs for the power button. Both the cases I have have 4 prongs for the power button. Whoops. Need a new switch I guess? I can't quite figure out the right terminology to google a new one.

EDIT It occurs to me they may only NEED 2 to function. Thoughts?

If you mean the spade connectors, you only need those two. Shorting them powers up the PSU. You just need to find two terminals on the switch that makes a connection when the switch is operated, and use them. Leave the other two terminals unconnected 😀

kaputnik wrote on 2020-11-05, 23:06:

tomexplodes wrote on 2020-11-05, 20:46:

cyclone3d wrote on 2020-11-04, 20:26:

Yep, that will work. […]
Show full quote

Yep, that will work.

If you don't mind waiting a while, you can get them on eBay from China for $3.25 a piece though.
https://www.ebay.com/itm/18AWG-20Pin-ATX-to-2 … 86/313021103999

There used to be a seller on eBay that sold the adapters that also had the -5v added (antronst) but he stopped selling them probably a year ago now. Not even finding that seller on eBay at all now.

One problem, which I realized too late. The only ones I can find (and the one I ordered https://www.amazon.com/7-Inch-20-Pin-Button-C … /dp/B075ZPWJBX/ ) only have 2 prongs for the power button. Both the cases I have have 4 prongs for the power button. Whoops. Need a new switch I guess? I can't quite figure out the right terminology to google a new one.

EDIT It occurs to me they may only NEED 2 to function. Thoughts?

If you mean the spade connectors, you only need those two. Shorting them powers up the PSU. You just need to find two terminals on the switch that makes a connection when the switch is operated, and use them. Leave the other two terminals unconnected 😀

I was hoping that was true, thanks!

Well, I believe I've ruled out the power supply. Got my cable today, everything's plugged in and working, NFSSE still won't load even the installer, Quake crashed nearly immediately. Just for fun, here's a picture of the page fault from Quake, in case someone knows how to decipher it. I think, though, I can probably assume that this CPU just isn't good. I'll swap back to my P90 and just have a much less powerful DOS machine, and just play the more intensive DOS games on my 98SE machine instead. Thank you everyone for helping me, I really appreciate it. Everyone here is just excellent all the time, in spite of my constant need for assistance, and it's just fantastic. Thank you all so much, in general, and for this specifically.

EDIT: so here's another weird thing. Doesn't fix anything, it's just weird; if I disable EMS through memmaker, Quake runs for a few seconds before crashing. I don't understand it.

Yet another post. After more screwing around, I think Quake and NFSSE think I don't have enough XMS. It's possible there's nothing wrong with my CPU at all. I'm confused, though, since I have 32MB RAM and ehhhhhhhhhh I dunno what I'm doing wrong anymore.

EDIT: So, out of desperation, I downloaded and installed QEMM 97. I let it automatically configure everything and so far, Quake's demo is still running, well beyond what it did previously. Memory management may have been my problem all along. I'll try NFSSE now and see what happens.

cyclone3d wrote on 2020-11-02, 21:08:

An interposer would also work for splitting the voltage. Not sure about the multiplier settings though as I haven't tried one on an interposer before.

Iam using an interposer board here.. Only could set a multiplier of 2x on a socket 5 SIS501 motherboard. So highest cpu clock i could get was 133 MHZ on a board which max was limited to 100 or 120 Mhz.

Dont know how the split voltage would setup correctly, but yes its possible to set 1.8 , 2.2, 2.5,2.8,2,9 and or 3.2 volt muliplier goes from 2 till 5.5. but in my motherboard is doesnt reconize anything above 2 x multiplier.

Well, after QEMM, everything runs jsut fine except for NFSSE and Jazz Jackrabbit so far. So, guess it was memory related? Don't know, losing ability to care anymore.

EDIT NOPE. Stuff is still broken. So, that's it, I'm done. It's a Pentium 90 with 16mb of RAM now. The end.