BitWrangler wrote on 2022-02-13, 15:51:

Those are them, yes those printed tables on the board tell you everything they do. ... with everything set on like it is in the picture, the CPU would run at 133 if it supported 2x... if you're trying to slow it down to 100 then turn switch 6 off.

It's running at 75mhz, i'm trying to bump it up to a 100.

Currently all the dip switches are set to OFF, i don't know why it looks like they're ON in the picture. If i understood correctly i have to turn switch 6 ON ?

john_popani wrote on 2022-02-13, 15:52:

BitWrangler wrote on 2022-02-13, 15:51:

Those are them, yes those printed tables on the board tell you everything they do. ... with everything set on like it is in the picture, the CPU would run at 133 if it supported 2x... if you're trying to slow it down to 100 then turn switch 6 off.

It's running at 75mhz, i'm trying to bump it up to a 100.

Currently all the dip switches are set to OFF, i don't know why it looks like they're ON in the picture. If i understood correctly i have to turn switch 6 ON ?

Sir, i'm eternally grateful to you, I turned switch 6 ON and it now registers @ a 100mhz. Thank you very much !!!!

You know, this is something I wanted to test for a long time, but I never got around to it.

In theory it should be possible to run a K6-233/ANR on a socket5 board. 😀

Yes, the K6 is a socket7 CPU and has a split voltage. However, for the K6-233 ANR the Vcore is 3.2V, only 0.1V off from that of socket5 CPUs (and actually 3.3V is within specs, because Vcore is specified as 3.2V +/- 0.145V, so 3.055V to 3.345V). Also, it will interpret a 1.5x multiplier as 3.5x, so on a 66MHz FSB it will run at 233MHz.

And then, there is the physical difference between the sockets: socket5 is 320 pins, socket7 is 321 pins. However the extra pin is only a "key" pin and not electrically connected. If that key pin on the K6 were bent or removed - or alternatively a small hole were drilled in the socket5 ZIF so that the extra pin fits, that would satisfy the mechanical constraint as well.

https://www.cpu-world.com/CPUs/K6/AMD-K6%2023 … -K6-233ANR.html

(I have a couple of K6-233 ANR, but I don't have a socket5 board to test this theory)

stamasd wrote on 2022-02-13, 17:15:

You know, this is something I wanted to test for a long time, but I never got around to it. […]
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You know, this is something I wanted to test for a long time, but I never got around to it.

In theory it should be possible to run a K6-233/ANR on a socket5 board. 😀

Yes, the K6 is a socket7 CPU and has a split voltage. However, for the K6-233 ANR the Vcore is 3.2V, only 0.1V off from that of socket5 CPUs (and actually 3.3V is within specs, because Vcore is specified as 3.2V +/- 0.145V, so 3.055V to 3.345V). Also, it will interpret a 1.5x multiplier as 3.5x, so on a 66MHz FSB it will run at 233MHz.

And then, there is the physical difference between the sockets: socket5 is 320 pins, socket7 is 321 pins. However the extra pin is only a "key" pin and not electrically connected. If that key pin on the K6 were bent or removed - or alternatively a small hole were drilled in the socket5 ZIF so that the extra pin fits, that would satisfy the mechanical constraint as well.

https://www.cpu-world.com/CPUs/K6/AMD-K6%2023 … -K6-233ANR.html

(I have a couple of K6-233 ANR, but I don't have a socket5 board to test this theory)

This sounds awesome but is way beyond my comprehension 😁

I’m just happy with my little speed bump

Hamby wrote on 2021-09-19, 14:09:

Does anyone know if it's possible to upgrade the CPU on a Gateway P5-75 system? Currently with a pentium 75mhz cpu, obviously.
What would be the max clock speed I could have with a faster CPU? Like, could I put, say, a 150mhz cpu in it?

Assuming that that is a socket five system with only one voltage regulator then your absolute fastest option would be a K63+ using a powerleap style interposer which you could probably get running anywhere between 400 and 500 MHz Depending on your front side bus speed options

Without modifying the board for dual plane voltage or getting a powerleap style interposer The fastest options are probably a winchip, MMX overdrive, or one of the k6/cyrix cpus that used 3.3-3.5v

I can confirm that you can put a K6-233ANR into a socket 5 board. My AP53-1, despite being Socket 7, isn't split-voltage, and electrically is more or less identical to Socket 5, and I have run that exact CPU in it in the past.

john_popani wrote on 2022-02-13, 15:21:

BitWrangler wrote on 2022-02-13, 14:10:

There are a few hundred motherboard models that use the i430FX chipset.

This is what i found on the motherboard. And these are the only jumpers it has

That AA-code on the sticker identifies this as an Intel OEM board. If I had to guess, based on the position of the CR2032 battery and the dipswitches, I'd say it was the Intel Advanced/ZP 'Zappa' - which was used by Gateway, but not exclusively; it was a common OEM board in the day.

If so, there's a lot of info on it here:
https://www.ultimateretro.net/en/motherboards/3136

And that confirms what BitWrangler already said based on the silkscreen: SW1/6 is the multiplier switch for BF0 (to switch between 1.5x and 2x). Set it to 'on' for 2x, which allows up to 133MHz (2x66MHz) with a suitable CPU.

However you seem to be labouring under a misconception if you think that you need to increase the multiplier to go from 75MHz to 100MHz, as both speeds (at least with Intel CPUs) work at 1.5x multiplier, just different FSB - 75MHz is 1.5x50MHz, 100MHz is 1.5x66MHz. So to install a Pentium 100, you want to set 1/7 and 1/8 to off and on respectively. It's possible to do 2x50MHz, but that is hopelessly inefficient, 1.5x66MHz will perform far better.

Are you intending to do this with the CPU you already have or a different one? It is possible that a (late) Pentium 75 will overclock to 100MHz, but by no means certain. You might have more luck by increasing voltage, from VS to VRE, by setting SW1/2 to on. It's probably a better idea though to get a real Pentium 100 instead.

dionb wrote on 2022-02-13, 23:47:

That AA-code on the sticker identifies this as an Intel OEM board. If I had to guess, based on the position of the CR2032 batter […]
Show full quote

john_popani wrote on 2022-02-13, 15:21:

BitWrangler wrote on 2022-02-13, 14:10:

There are a few hundred motherboard models that use the i430FX chipset.

This is what i found on the motherboard. And these are the only jumpers it has

That AA-code on the sticker identifies this as an Intel OEM board. If I had to guess, based on the position of the CR2032 battery and the dipswitches, I'd say it was the Intel Advanced/ZP 'Zappa' - which was used by Gateway, but not exclusively; it was a common OEM board in the day.

If so, there's a lot of info on it here:
https://www.ultimateretro.net/en/motherboards/3136

And that confirms what BitWrangler already said based on the silkscreen: SW1/6 is the multiplier switch for BF0 (to switch between 1.5x and 2x). Set it to 'on' for 2x, which allows up to 133MHz (2x66MHz) with a suitable CPU.

However you seem to be labouring under a misconception if you think that you need to increase the multiplier to go from 75MHz to 100MHz, as both speeds (at least with Intel CPUs) work at 1.5x multiplier, just different FSB - 75MHz is 1.5x50MHz, 100MHz is 1.5x66MHz. So to install a Pentium 100, you want to set 1/7 and 1/8 to off and on respectively. It's possible to do 2x50MHz, but that is hopelessly inefficient, 1.5x66MHz will perform far better.

Are you intending to do this with the CPU you already have or a different one? It is possible that a (late) Pentium 75 will overclock to 100MHz, but by no means certain. You might have more luck by increasing voltage, from VS to VRE, by setting SW1/2 to on. It's probably a better idea though to get a real Pentium 100 instead.

Thank you for this explaination,

I bought a pentium 100, but when i put it in, before turning Switch 6 ON, it registered at 75mhz, so i thought the guy who was selling it didn't know what he had or it was one of those rebranded 75s which i heard about. I have to install it again now and check how it performs. Switches 7 and 8 were set to OFF by default, so I won't have to touch them and switch 6 will remain ON I suppose. I'll do this tonight, after work, and post the results.

The background behind that text looks sketchy as all hell, some of the white letters are slightly smudged too, doesnt look real, neither do the markings on the bottom.

TrashPanda wrote on 2022-02-14, 08:14:

The background behind that text looks sketchy as all hell, some of the white letters are slightly smudged too, doesnt look real, neither do the markings on the bottom.

Exactly, it could very well be a rebranded 75 so i'll be on the lookout for another one, just in case. This one was simply too tempting to pass on, given it's brand new 😁

john_popani wrote on 2022-02-14, 08:50:

TrashPanda wrote on 2022-02-14, 08:14:

The background behind that text looks sketchy as all hell, some of the white letters are slightly smudged too, doesnt look real, neither do the markings on the bottom.

Exactly, it could very well be a rebranded 75 so i'll be on the lookout for another one, just in case. This one was simply too tempting to pass on, given it's brand new 😁

Well its reboxed, it may not actually be new.

Too many red flags on this one honestly, I would get another and uhh .. shuffle this one off to the Evilbay.

john_popani wrote on 2022-02-14, 08:08:

[...]

Thank you for this explaination,

I bought a pentium 100, but when i put it in, before turning Switch 6 ON, it registered at 75mhz, so i thought the guy who was selling it didn't know what he had or it was one of those rebranded 75s which i heard about.

Er, these are vintage systems, nothing happens automatically. If you leave the jumpers at 75MHz, it runs at 75MHz, even if it's a 200MHz CPU. If you want it to run at 100MHz, you need to set it there.

I have to install it again now and check how it performs. Switches 7 and 8 were set to OFF by default, so I won't have to touch them and switch 6 will remain ON I suppose. I'll do this tonight, after work, and post the results.

Again, that is NOT the correct setting for a Pentium 100. It should be set to 1.5x66MHz, so 1/6 off and 1/8 on. 1/7 and 1//8 were off "by default" as the Pentium 75 uses a 50MHz FSB so were correct for it. Not for a Pentium 100.

It's premature to suspect the seller if you haven't set the board correctly for the CPU it is supposed to be.

I have the horizontal desktop style case Gateway 2000 P5-75 and I do recall changing DIP switches to overclock to 90mhz. I thiiiink I could have gone further than that but didn't really want to stress the machine out - I've owned it from new and am a bit attached to it! I dropped it back to 75mhz not long after.

As far as I can recall, there's a silkscreened instructional table printed on the motherboard showing what the different dip positions do.

stamasd wrote on 2022-02-13, 17:15:

You know, this is something I wanted to test for a long time, but I never got around to it.

In theory it should be possible to run a K6-233/ANR on a socket5 board. 😀

Yes, the K6 is a socket7

My socket 5 boards had very wimpy linear regulators, even after adding a heat sync and fan things would get hot enough to smoke.

Likely need to update the regulator on most socket 5 boards to get it up and running

dionb wrote on 2022-02-14, 09:06:

Er, these are vintage systems, nothing happens automatically. If you leave the jumpers at 75MHz, it runs at 75MHz, even if it's […]
Show full quote

john_popani wrote on 2022-02-14, 08:08:

[...]

Thank you for this explaination,

I bought a pentium 100, but when i put it in, before turning Switch 6 ON, it registered at 75mhz, so i thought the guy who was selling it didn't know what he had or it was one of those rebranded 75s which i heard about.

Er, these are vintage systems, nothing happens automatically. If you leave the jumpers at 75MHz, it runs at 75MHz, even if it's a 200MHz CPU. If you want it to run at 100MHz, you need to set it there.

I have to install it again now and check how it performs. Switches 7 and 8 were set to OFF by default, so I won't have to touch them and switch 6 will remain ON I suppose. I'll do this tonight, after work, and post the results.

Again, that is NOT the correct setting for a Pentium 100. It should be set to 1.5x66MHz, so 1/6 off and 1/8 on. 1/7 and 1//8 were off "by default" as the Pentium 75 uses a 50MHz FSB so were correct for it. Not for a Pentium 100.

It's premature to suspect the seller if you haven't set the board correctly for the CPU it is supposed to be.

I set the board as per your recommendation and the new cpu runs at 100mhz. The benchmark is also ever so slightly better than the original one with the overclock. So i guess i'll be keeping the new one. I managed to connect its fan to the power, so hopefully it's going to keep the temperature at a good level.

I'm going to try a new gpu as well, because some games are still running worse than i remember. It has an Ati mach64 now, which i'll change with an S3 Virge. It will be interesting to see if there's an improvement.

Thanks again 😀