It should work, after all, just set the jumpers accordingly. Though beware because some motherboards can act fussy with fast CPUs, though it seem to be a rare occurrence.

There is no practical difference between P54C and P54CS as far as motherboard compatibility is concerned.You'll be fine.

The worst that could happen would probably involve wounding yourself or a loved one on a pin of the old CPU, the wound getting septic and dying in slow agony. However that isn't exactly very likely 😉

All you need to do is swap out the CPU and change the relevant jumpers. Currently bus speed is set to 50MHz, that needs to go up to 66MHz. Theoretically you also need to change the multiplier jumper from the position for 1.5 to the position for 2.0, but in this case it won't matter as the SY022 P133 is multiplier-locked on 2x anyway.

Everything else can remain the same. The only outside corner case you might hit is that cache or RAM chips can't handle the faster 66MHz bus speed and the system becomes unstable. You can check for what they are rated for by looking at the last digit on the chips' model# row. On the RAM chips it will be -7 or -6. -6 implies 60ns and is fine for 66MHz (and above), -7 implies 70ns and is theoretically good up to 60MHz, but not 66MHz. It will probably work, but in case of issues, it's the first thing to look at. For cache the marking to look for is -15. That's 15ns (cache SRAM is faster than DRAM, that's its job), and is good for 66MHz. Anything above that might not work.

najls wrote on 2020-01-30, 21:33:

I have no idea if that has any significance - P54C vs P54CS. I mean, it's still Socket 7 and the clock speed should be supported.

My question isn't really if it will work, but rather, what's the worst that can happen if it doesn't?

The P54C was 3.3v and 50uM die type, the P54CS was 3.3v and 35uM die type. Basically just smaller sized transistors inside but functionally and electrically the same. You should have no problems swapping them. Just make sure you install it correctly and pull the power before swapping. Use a heatsink + fan for longer life.

edit: worst that could happen is you try to install it in the socket wrong or have power applied when you swap....

worst that could happen is you try to install it in the socket wrong

You can't install any Pentium CPU wrong side, including Pentium Overdrive. It's idiot proof, although not excessive force proof.

The Serpent Rider wrote on 2020-01-31, 04:36:

worst that could happen is you try to install it in the socket wrong

You can't install any Pentium CPU wrong side, including Pentium Overdrive. It's idiot proof, although not excessive force proof.

Yeah well I have seen the results of somone swapping Pentium cpu while board was in a case and it was not right but they didn't know it. One corner was up but they powered it anyway. You can guess the result.

Whenever somebody designs something to be more idiot-proof, we just get better idiots...

The Serpent Rider wrote on 2020-01-31, 04:36:

You can't install any Pentium CPU wrong side, including Pentium Overdrive. It's idiot proof, although not excessive force proof.

Yeah, I'd say this is the only part I'm sure I won't mess up 😀

dionb wrote on 2020-01-30, 22:01:

The worst that could happen would probably involve wounding yourself or a loved one on a pin of the old CPU, the wound getting septic and dying in slow agony.

Will be stocking up on antiseptics though.

dionb wrote on 2020-01-30, 22:01:

On the RAM chips it will be -7 or -6. -6 implies 60ns and is fine for 66MHz (and above), -7 implies 70ns and is theoretically good up to 60MHz, but not 66MHz.

Very good advice! Will make sure to check this out. Thanks!

Horun wrote on 2020-01-31, 04:28:

Use a heatsink + fan for longer life.

Check! I'm using a heatsink and fan for the P75 right now and I even put on cooling paste, but I kinda had the feeling that was a bit excessive. Was it? 😀

mpe wrote on 2020-01-30, 21:40:

There is no practical difference between P54C and P54CS as far as motherboard compatibility is concerned.You'll be fine.

That is pretty much what I wanted to hear. Learning about things is nice. Thanks!

The Serpent Rider wrote on 2020-01-31, 04:36:

worst that could happen is you try to install it in the socket wrong

You can't install any Pentium CPU wrong side, including Pentium Overdrive. It's idiot proof, although not excessive force proof.

well, I've seen a socket 7 CPU inserted into socket 370 before...

dionb wrote on 2020-01-30, 22:01:

The worst that could happen would probably involve wounding yourself or a loved one on a pin of the old CPU, the wound getting septic and dying in slow agony.

It's true. This happened to me.

najls wrote on 2020-01-31, 07:39:

Check! I'm using a heatsink and fan for the P75 right now and I even put on cooling paste, but I kinda had the feeling that was a bit excessive. Was it? 😀

The HSF situation on older CPUs like this are a little more forgiving than what we have now. No, you don't absolutely need thermal paste - but, if you have some of the plain white grease that you get with any passive cooler ever, it doesn't hurt to add a dab of it. Not too much. If you mount the heatsink and your CPU looks like a burger ad, you've gone too far. Just a thin thin layer will do.

The other common question is "how much is enough cooling?" In some cases, just a heatsink is OK. Usually you need the fan. It depends on several variables, like the profile of the heatsink, airflow in the case, ambient temperature, etc. Here's my definitive test: When the system has been running for five minutes, give the heatsink a light touch. Is your finger OK? Then your cooling is adequate. Better yet, if it's warm but not uncomfortably hot, then you're all set.

dionb wrote on 2020-01-30, 22:01:

All you need to do is swap out the CPU and change the relevant jumpers. Currently bus speed is set to 50MHz, that needs to go up to 66MHz. Theoretically you also need to change the multiplier jumper from the position for 1.5 to the position for 2.0, but in this case it won't matter as the SY022 P133 is multiplier-locked on 2x anyway.

From what I've read I guess some of them were locked, but not all. My SY022 isn't locked.

If you get it working at 133MHz then try changing the jumper to 2.5x and see what happens. SY022 was a late revision CPU so if yours isn't locked it will probably run easily at 166MHz.

Only thing I am bit confused about is that you said it is from around 1993, but pentium 75Mhz was released in 1994 as far as I know and that microstar motherboard seems newer than 1993 to me as well.

shamino wrote on 2020-02-01, 05:51:

dionb wrote on 2020-01-30, 22:01:

All you need to do is swap out the CPU and change the relevant jumpers. Currently bus speed is set to 50MHz, that needs to go up to 66MHz. Theoretically you also need to change the multiplier jumper from the position for 1.5 to the position for 2.0, but in this case it won't matter as the SY022 P133 is multiplier-locked on 2x anyway.

From what I've read I guess some of them were locked, but not all. My SY022 isn't locked.

If you get it working at 133MHz then try changing the jumper to 2.5x and see what happens. SY022 was a late revision CPU so if yours isn't locked it will probably run easily at 166MHz.

Some SY022 CPUs unlocked? You live and learn 😉

...except this is an So5 board, so no BF1 multiplier jumper. There isn't a 2.5x setting, to do that you'd have to mod CPU or socket to conect BF1 pin to Vss/GND.

SirNickity wrote on 2020-01-31, 20:42:

The other common question is "how much is enough cooling?" In some cases, just a heatsink is OK. Usually you need the fan. It depends on several variables, like the profile of the heatsink, airflow in the case, ambient temperature, etc. Here's my definitive test: When the system has been running for five minutes, give the heatsink a light touch. Is your finger OK? Then your cooling is adequate. Better yet, if it's warm but not uncomfortably hot, then you're all set.

I went with the heatsink and fan and some cooling paste. There's no additional cooling in the case, but this seems fine. Thanks for the pointers!

shamino wrote on 2020-02-01, 05:51:

If you get it working at 133MHz then try changing the jumper to 2.5x and see what happens. SY022 was a late revision CPU so if yours isn't locked it will probably run easily at 166MHz.

Might give that a shot, though I'm not actually sure I need that much speed 😀 I actually havn't benchmarked it yet either. Any suggestions for realiable software to use (in Windows 95)?

Baoran wrote on 2020-02-01, 10:00:

Only thing I am bit confused about is that you said it is from around 1993, but pentium 75Mhz was released in 1994 as far as I know and that microstar motherboard seems newer than 1993 to me as well.

I may very well just be wrong on this point. I've been having a hard time finding info on the mobo. It may very well be from 1994! Not sure if the P75 was the processor it originally came with either.

dionb wrote on 2020-01-30, 22:01:

All you need to do is swap out the CPU and change the relevant jumpers. Currently bus speed is set to 50MHz, that needs to go up to 66MHz. Theoretically you also need to change the multiplier jumper from the position for 1.5 to the position for 2.0, but in this case it won't matter as the SY022 P133 is multiplier-locked on 2x anyway.

I have here a late produced (produced in 2001!) Pentium 133 SY022 stepping with free 2.5x and 3x multipliers! Also runs fine with 200 MHz and the default VCore of 3,3V. Why are some SY022 unlocked, because I have thought that all are locked? I also had a P133 (produced in 1997) with the same stepping that gaves a Blackscreen, after setting the multiplier higher than 2x.

As far as I know all Pentium are unlocked except for overdrives.

Intel started locking CPUs in 1998 (Pentium II).

mpe wrote on 2020-05-06, 20:19:

As far as I know all Pentium are unlocked except for overdrives.

Intel started locking CPUs in 1998 (Pentium II).

There are definitely locked Pentium 133 SY022 CPUs out there - those things didn't get a reputation for nothing. Less certain, but I recall some MMX CPUs also didn't want to accept some multiplier settings.

In fact here's one of the engineers who worked on it giving a not very specific apology 😜
https://forums.anandtech.com/threads/pentium- … 70/post-4349447
https://forums.anandtech.com/threads/pentium- … 70/post-4351373

Yeah, I'm pretty sure they actually started locking chips in 1997. As the poster above stated, it was PMMX. I remember some PMMX chips were locked and others not. Maybe original Pentium chips produced in 1997 were too, but this is new to me.

I am ready to start testing the Pentium 133 too.

I am currently using a Pentium 75 in an Intel 430vx motherboard.

I am going to put the Pentium 133 in an Intel 430tx motherboard.