My EXP-4045 board allows me to have any combination of 25, 33, or 40 mhz Base clock/FSB speed, with a 1x, 2x, 2.5x, or 3x multiplier, allowing for any combination of those, including 25Mhz. As far as I am aware, all 486 chips have this same ability (Of course overclocking isn't gonna work that well on older chips) with the exception of 486 Overdrives, and OEM boards with the clock speed locked.

You can most definitely run a DX4-100 at all of those speeds (Even 40x3, which is what I use on my Am486-DX4-100-SV8B)

Have you actually run your DX/4 with a 1x multiplier? That would be cool if you could actually run it a 1x33Mhz. I was under the impression DX2s were locked at 2x and DX4s were locked at 3x. Gerwin's results seem to indicate it can run at 2x and 3x, but not 1x. Still, my point is more about it being a bother to change jumpers (unless you get crazy with making switches like Phil did). It takes more effort to downclock the DX4.

I have nothing against the DX4, it was the CPU I ran in the mid-90s (my upgrade path back then was SX/25->DX4/100->P120).

@Ampera
It is never really about what multipliers a particular motherboard supports, it is about what multipliers a particular CPU supports. If you can get a 486DX4-100 running at 1x or 2.5x I would love to see details and/or a SpeedSys screenshot of that.

Yes it does depend on the CPU. Wikipedia has a good list of which CPUs have support for 2x and 3x. 1x though doesn't exist AFAIK.

Yeah, I stand corrected here. 1x doesn't exist. I just thought it did. This doesn't mean something could be hacked up somehow, but without messing with the jumpers a whole lot, 1x is impossible.

This means the slowest speed is 25mhz x2 for a DX4-100. You could of course also have a DX-40 standing by and use that when you want to slow it down. It's incredibly easy to swap out.

Even still, 50Mhz isn't bad, and with the turbo button, cache disabled, and some bios tweaks, you could probably get it running at a DX-25 speed or maybe even slower.

This is from a VOBIS advert for christmas sale in 1993. Prices are in DM:

So P60 for just 6999,- DM and there is also this nice Alpha system for just 9998,- DM

at the same time on the front page of this advert brochure:

Is a 486DX2-66 for just 2999,- DM.

OT: And there is also the Apple Newton there...

Yea, that's the thing: Pentiums were more than twice as expensive as a 486DX2-66 back in the day... and even that 486DX2-66 wasn't all that cheap to begin with.
As I said, those Pentiums were server/workstation class hardware, not something a consumer would generally buy. You could buy a small car for that amount of money.

Scali wrote:

Yea, that's the thing: Pentiums were more than twice as expensive as a 486DX2-66 back in the day... and even that 486DX2-66 wasn't all that cheap to begin with.
As I said, those Pentiums were server/workstation class hardware, not something a consumer would generally buy. You could buy a small car for that amount of money.

My dad bought a second hand 4 year old 316i for 6000 dm back in 1994... damn pc's were expensive back then. Either that or cars were cheaper then they are today.

kanecvr wrote:

Scali wrote:

Yea, that's the thing: Pentiums were more than twice as expensive as a 486DX2-66 back in the day... and even that 486DX2-66 wasn't all that cheap to begin with.
As I said, those Pentiums were server/workstation class hardware, not something a consumer would generally buy. You could buy a small car for that amount of money.

My dad bought a second hand 4 year old 316i for 6000 dm back in 1994... damn pc's were expensive back then. Either that or cars were cheaper then they are today.

I always thought that Pentium was expensive cause the performance jump and complexity was big compared to the previous generations of cpu. Also chipset with PCI support and newer PCI video cards. With the Pentium every other components were differents.

But thinking at those times, things were built to last more than are today. I had a 386SX from 1994 to 1999 without any modifications (but the ram upgrade) and generally you'd never think changing somethings that still worked. Same thing with TV at home that would last for years and when not they were just repaired. Nowdays just think at how much smartphones and tv are replaced.

386SX wrote:

I always thought that Pentium was expensive cause the performance jump and complexity was big compared to the previous generations of cpu. Also chipset with PCI support and newer PCI video cards. With the Pentium every other components were differents.

It was a different business model than today.
The 386 and 486 were also extremely expensive when they came out (if you can find some German adverts from around 1989 with the first 486, they'd probably also cost around 7000 DM). As I say, they were the Xeons of their time.
Back then, the mainstream 'Core', 'Pentium' or 'Celeron' CPUs were simply older generation chips.
These days it's different, because manufacturers can vary a lot more with clock speeds, cache sizes, number of cores etc. So their strategy is to develop a single modular architecture, and then build various product lines from that, from mobile devices to notebooks, desktops, servers and even HPC.
Back then it made more sense to just keep the 486 as a 'low budget' Pentium, rather than trying to strip the Pentium architecture down.
Basically the introduction of the Pentium is what made the 486 drop in price and made the 486 mainstream. Before 1993, most gamers would still use 286 or 386 machines.

I am not sure, you could buy pentium with pci card in 93, maybe in the veryvery late 93, and just a couple of slow vga chipsets released at the first time. It was more typical in the early 94. Before that, they came with eisa, possibly the dx2-66 with a fast vlb card (eg wd90c33 with 0ws) could be faster for games.

Most of the socket4 mainboards what you can find, from the late 94, they sold them in 95. I guess a 93 manufactured pentium board with pci is super rare (intel batman first edition).

To overclock Amd to 200 is rare and hard to go for and even motherboard can be a issue too. Most 5x86 Amd hit 160 most of time. The easiest way is Amd 486DX4 120 if you dont want to overclock and most compatible with old boards.

Cheers,

I don't think it would be 100% stable at 200, not after a hour of gaming anyway

I think I'd pair a Pentium 75 and an AOpen AP57 motherboard.
This motherboard supports memory bank with half width, this means it runs a Pentium with a single PS/2 stick.

fyi, it exist 😉