about 100W of difference 😀

An advantage with Pentium III motherboards is being able to use some older ISA sound cards and having 50-66 MHz FSB as an option which (depending on the CPU multiplier) is handy for dealing with speed-sensitive software.

rasz_pl wrote on 2024-06-26, 12:58:

about 100W of difference 😀

probably the main difference!

in principal there should be no other difference, there should be no fundamental difference anyway - just quirks with drivers and motherboards

are there common or even niche dos games that 'require' isa cards and also benefit from anything over the mighty 450mhz of the katmai? (the minimal p3)

P4 chipsets don't natively support ISA, so you're dependent on the PCI to ISA bridge chip. Some support ISA DMA, others don't. If they don't they're pretty useless for DOS. P3 chipsets (other than Intel's i820/840) all natively support ISA including ISA DMA, so no such worries. It just works (TM)

As for throttling, the Via C3 Nehemiah is throttle king. See: Every Speed Reference Point on a Single CPU - VIA C3 Nehemiah Only downside is that its top performance might be too slow (comparable to a P3-500 or so). On a P4, you have Throttle and it does what it should do to slow the system down, but doesn't get the CPU as aggressively low as is possible on Nehemiah.

For short, nothing to gain with a P4 but so much to loose. P3 is the last thing, that is DOS compatible. After that, it os DOS experimental. And the running/experimenting of Windows 9x, also much better. And yes, power consumption.

Late ISA motherboards (especially socket 775) use PCI-ISA chip bridges while Pentium 3 boards have native ISA support in chipsets. That means better compatibility with ISA cards.
It is not a problem to find 2-4 ISA slots on Slot1 motherboards, while on Pentium 4 boards you rarely see more then 1 ISA slot.
Pentium 3 can achieve lower clocks without throttling. It works smoother generally.
VIA C3 on Slot1 or socket 370 motherboard is super flexible though slower than P3.
PC case for Pentium 3 system can be smaller because of lesser heat.
Most of Socket 478 systems I've ever seen worked with the sound of vacuum cleaner.
Fast Pentium 4 need good cooler. For socket 478 it is rather problematic to find.
A lot of Pentium 3 motherboard have SB-Link connector which improved compatibility with Dos when using Yamaha or Solo-1 cards. Never seen this thing on Pentium 4 boards.
Later socket 478 boards and all 775 boards can't accept old AGP video cards with 3.3v (Voodoo 5, Riva 128, TNT, S3 Trio 3d, S3 Savage 3d, SIS 6326 and much more) while almost all of Pentium 3 boards can do it.

dionb wrote on 2024-06-26, 13:18:

As for throttling, the Via C3 Nehemiah is throttle king. See: Every Speed Reference Point on a Single CPU - VIA C3 Nehemiah Only downside is that its top performance might be too slow (comparable to a P3-500 or so). On a P4, you have Throttle and it does what it should do to slow the system down, but doesn't get the CPU as aggressively low as is possible on Nehemiah.

Kruton 9000 wrote on 2024-06-26, 13:38:

VIA C3 on Slot1 or socket 370 motherboard is super flexible though slower than P3.

I can concur with the flexibility the VIA C3 Nehemiah CPU offers when slowing down the computer. Plus, the D-cache can be disabled with CPUSPD.

The performance at 1.2 GHz is quite closer to a PIII-750, at least on the ASUS motherboard that I'm currently using.

I have a V5 5500 in my P3 setup. When I go S775, I lose the ability to use it or the lesser brothers. V2SLI might still work, PCI sockets galore, no IRQ needed.

I can throttle my P3 down to around 386-16. It can emulate early 90s in speed. But from there to 500 MHz is a vast gap it can't cover. I can pick 500 MHz, 750 and 1000. Or I pick like 386-16, 25, 33. That is all I found, without swapping in a P2.

A P3 isn't variable in speed really (at least I found nothing that works well), but it can offer great variability in hardware. So if you are a tinkerer, you have OPTIONS. As I just experienced myself, when you go S775, you don't have options. The is the best card for this and for that. Things seem to have clearcut best solutions. Not with a P3. (unless you have many ISA slots)

With S775 and c2d, CPUs can be had quiet again. But now the fitting GPUs act up. I was amazed by the heat even the 4200ti created. It has a commercial "batman" replacement cooler, but still.

gerry wrote on 2024-06-26, 13:11:

are there common or even niche dos games that 'require' isa cards and also benefit from anything over the mighty 450mhz of the katmai? (the minimal p3)

The main ones I know of are DOS Quake in software mode and the build-engine games (e.g. Duke 3D, Shadow Warrior, Blood). Running these at higher resolutions, they do seem to take advantage of the faster CPU clock speeds.

Cyberdyne wrote on 2024-06-26, 13:35:

For short, nothing to gain with a P4 but so much to loose. P3 is the last thing, that is DOS compatible. After that, it os DOS experimental. And the running/experimenting of Windows 9x, also much better. And yes, power consumption.

DOS works fine on a P4.

Gmlb256 wrote on 2024-06-26, 13:10:

An advantage with Pentium III motherboards is being able to use some older ISA sound cards

dionb wrote on 2024-06-26, 13:18:

P4 chipsets don't natively support ISA, so you're dependent on the PCI to ISA bridge chip. Some support ISA DMA, others don't. If they don't they're pretty useless for DOS. P3 chipsets (other than Intel's i820/840) all natively support ISA including ISA DMA, so no such worries. It just works (TM)

Kruton 9000 wrote on 2024-06-26, 13:38:

Late ISA motherboards (especially socket 775) use PCI-ISA chip bridges while Pentium 3 boards have native ISA support in chipsets. That means better compatibility with ISA cards.

Wait a minute...

*No* P4 chipset supports DMA, right?
Some - but not all - P4 PCI-ISA bridges *do* support DMA, right?

What's the practical difference between DMA support in the chipset vs. in the PCI-ISA chip?
Which ISA cards work with the latter approach, and which don't work?

Kruton 9000 wrote on 2024-06-26, 13:38:

It is not a problem to find 2-4 ISA slots on Slot1 motherboards, while on Pentium 4 boards you rarely see more then 1 ISA slot.

I have three different models of P4 boards that have 2 ISA slots each.

Conversely, a number of the P3 boards I have (Slot 1/Socket 370) only have a single ISA slot.

Most of Socket 478 systems I've ever seen worked with the sound of vacuum cleaner.

System noise is about the choice of fans, not the platform. I've had Tandy 1000 computers that sound like vacuum cleaners with stock fans.

Later socket 478 boards and all 775 boards can't accept old AGP video cards with 3.3v (Voodoo 5, Riva 128, TNT, S3 Trio 3d, S3 Savage 3d, SIS 6326 and much more) while almost all of Pentium 3 boards can do it.

AGP compatibility is a good point. The P4 boards I have are limited in that respect.

At the same time, I don't imagine there is a lot of need to put most older AGP cards in a faster P4. That would just bottleneck the system in terms of GPU performance.

rasz_pl wrote on 2024-06-26, 12:58:

about 100W of difference 😀

Not all P4 chips are *that* bad. 🤣

Northwood and Cedar Mill processors can have a TDP in the ~50-70W range. Hotter than a P3, but not excessively so.

ux-3 wrote on 2024-06-26, 14:01:

I can throttle my P3 down to around 386-16. It can emulate early 90s in speed. But from there to 500 MHz is a vast gap it can't cover. I can pick 500 MHz, 750 and 1000. Or I pick like 386-16, 25, 33. That is all I found, without swapping in a P2.

A P3 isn't variable in speed really (at least I found nothing that works well)

This is weird. Are there really no jumpers on your motherboard that set the bus to 66 MHz? On many boards even frequencies 75, 83 and more are available. Or Pentium 3 doesn't work with lower FSB?

ux-3 wrote on 2024-06-26, 14:01:

I can throttle my P3 down to around 386-16. It can emulate early 90s in speed. But from there to 500 MHz is a vast gap it can't cover. I can pick 500 MHz, 750 and 1000. Or I pick like 386-16, 25, 33. That is all I found, without swapping in a P2.

My experience with my Cedar Mill P4 is I have throttled it down to 286-12 MHz speeds. It can generally cover mid-range 486 (with cache disabled) down to 286. There is more of a gap above that, although Pentium speeds are achievable with ODCM / ACPI throttling.

A P3 isn't variable in speed really (at least I found nothing that works well), but it can offer great variability in hardware. So if you are a tinkerer, you have OPTIONS. As I just experienced myself, when you go S775, you don't have options. The is the best card for this and for that. Things seem to have clearcut best solutions. Not with a P3. (unless you have many ISA slots)

I think it depends on what we mean by options here. The one limitation on the P4 boards is the AGP slot, which won't support earlier AGP cards.

On the flipside, the other I/O options tend to be more expansive on the P4 boards. For example, both the DFI G7S620-N-G and IMB200 motherboards I'm using have dual SATA ports, in addition to AGP/PCI/ISA, USB 2.0, PS/2, build-in VGA, parallel, LAN, and 4x serial ports. The DFI board even has dual Gigabit LAN ports.

Just having ISA slots + SATA on a single board is something you won't find on a P3 board.

Shponglefan wrote on 2024-06-26, 14:26:

gerry wrote on 2024-06-26, 13:11:

are there common or even niche dos games that 'require' isa cards and also benefit from anything over the mighty 450mhz of the katmai? (the minimal p3)

The main ones I know of are DOS Quake in software mode and the build-engine games (e.g. Duke 3D, Shadow Warrior, Blood). Running these at higher resolutions, they do seem to take advantage of the faster CPU clock speeds.

ah yes, i do remember trying higher res in quake on a celeron 500 i had once but felt the 'return on extra pixels' was poor in terms of gameplay, ie didn't actually look much better. everything DOS seemed to run very fast on that machine though - but i guess there are some games with settings that can keep on demanding more. I'd guess most retro builders would focus more on the P3 at the 1Ghz speed than the good old katmai these days though

Wouldn't the Throttle Blaster project mitigate those gaps on both P4s and P3s platforms?

I'm surprised that project didn't get much traction here on Vogons

Pino wrote on 2024-06-26, 16:23:

Wouldn't the Throttle Blaster project mitigate those gaps on both P4s and P3s platforms?

I'm surprised that project didn't get much traction here on Vogons

The P4 does have native throttling capabilities via both ODCM and ACPI. This is the same a throttle blaster (controlling the STPCLK# pin) on the processor, but with fewer frequency options.

It's a question as to how well it works for individual games. For the games that I have tested, they tend to work without issues. The only game I ran into problems was audio slow-down in Ultima 7 specifically during the earthquake (screen shake) effect.

I have three different models of P4 boards that have 2 ISA slots each.

It's cool. Honestly, I never seen even one P4 ISA motherboard in my country.

System noise is about the choice of fans, not the platform. I've had Tandy 1000 computers that sound like vacuum cleaners with stock fans.

I know, but generally good fans for socket 478 aren't available. They were bad in Socket 478 times and later fans were rarely compatible with it. The problem can be solved, but it's a problem. Another thing Socket 775.