Which version of the DX4-75 are we talking about here .. the ceramic normal version or the even more rare overdrive model with 16kb of L1 cache ?

And yeah the extra cache makes a fair bit of difference.

As for interesting ...the 486 DX-50 (Note its not a DX2) is a more interesting CPU to discuss, its the only 486 with a 50Mhz FSB, the DX4-75 is only interesting because its rare but other than that the DX4-100 is a better CPU and far easier to obtain.

the qfp version i think, is not socketed but soldered directly on a small daughterboard.

AlessandroB wrote on 2024-02-03, 21:43:

the qfp version i think, is not socketed but soldered directly on a small daughterboard.

Thats an odd little CPU then, do you have some pics ?

Not sure I have ever seen a DX4-75 that wasnt a standalone CPU.

Which one is it?
SK052, SK100, SX870, SX883 or another number?

Dx4-75’s were marketed to death in laptops. They seemed to be common.

Besides being an overdrive for obsolete 25mhz 486’s I’ve never understood the point of this chip in “new desktop “ computers

Slower cache, ram, video and hard drive performance meaning the venerable DX2-66 could run side by side .

I’ve never tested it but have to guess these were easy to overclock.

Now if you want to talk rarer, the DX4-90’s were a thing

Also originally Intel itself included DX3 CPUs in the roadmap, a DX3-75 would have made more sense but Intel skipped it

rmay635703 wrote on 2024-02-03, 23:17:

Besides being an overdrive for obsolete 25mhz 486’s I’ve never understood the point of this chip in “new desktop “ computers

Slower cache, ram, video and hard drive performance meaning the venerable DX2-66 could run side by side .

Marketing? The DX4 was never intended to be a flagship (the Pentium was already out), so if you can advertise 9 extra MHz and if the large OEMs can perhaps use slower (read: cheaper) parts in the rest of the system than in a DX2/66 system, that sounds like a win...

And actually, I would go one step further - if they already had motherboard designs that were optimized for a 25MHz bus that they could stick a DX4 onto with minimal adjustments, while that design couldn't handle a 33MHz bus, that means they get an extra year of life out of that design...

Large OEMs have always, always wanted to cut costs (and deliver the most-MHz and the most megabytes with the least everything-else they can get away with), whether at that time, at the turn of the millennium (just how many i810 systems were shipped with high-MHz CPUs at top dollar?), or today...

rmay635703 wrote on 2024-02-03, 23:17:

Dx4-75’s were marketed to death in laptops. They seemed to be common. […]
Show full quote

Dx4-75’s were marketed to death in laptops. They seemed to be common.

Besides being an overdrive for obsolete 25mhz 486’s I’ve never understood the point of this chip in “new desktop “ computers

Slower cache, ram, video and hard drive performance meaning the venerable DX2-66 could run side by side .

I’ve never tested it but have to guess these were easy to overclock.

Now if you want to talk rarer, the DX4-90’s were a thing

Also originally Intel itself included DX3 CPUs in the roadmap, a DX3-75 would have made more sense but Intel skipped it

AFAIK DX3 was planned to have the multiplier of 2.5. So DX2 multiplier 2. DX3 multiplier 2.5. DX4 multiplier 3.
Not really straight forward, nobody understands the logic behind. And then a DX3 was never produced. Except one: the PODP 63 and 83, those had a multiplier of 2.5, but anyway the multiplier was hardcoded.
Are you sure a DX3-75 was in the roadmap? So bus = 30MHz. So even more exotic than a DX4-90?
EDIT:
Funny that wikichip.org also mentions 2.5 multiplier. It never existed

VivienM wrote on 2024-02-03, 23:34:

Marketing? The DX4 was never intended to be a flagship (the Pentium was already out), so if you can advertise 9 extra MHz and if […]
Show full quote

rmay635703 wrote on 2024-02-03, 23:17:

Besides being an overdrive for obsolete 25mhz 486’s I’ve never understood the point of this chip in “new desktop “ computers

Slower cache, ram, video and hard drive performance meaning the venerable DX2-66 could run side by side .

Marketing? The DX4 was never intended to be a flagship (the Pentium was already out), so if you can advertise 9 extra MHz and if the large OEMs can perhaps use slower (read: cheaper) parts in the rest of the system than in a DX2/66 system, that sounds like a win...

And actually, I would go one step further - if they already had motherboard designs that were optimized for a 25MHz bus that they could stick a DX4 onto with minimal adjustments, while that design couldn't handle a 33MHz bus, that means they get an extra year of life out of that design...

Large OEMs have always, always wanted to cut costs (and deliver the most-MHz and the most megabytes with the least everything-else they can get away with), whether at that time, at the turn of the millennium (just how many i810 systems were shipped with high-MHz CPUs at top dollar?), or today...

I think the DX4-100 from Intel was a flagship.
But they delayed the release date on purpose, so Pentium 90 and 100 were simultaneously released with Intel DX4-100. Of course Pentium 90 is always faster than the Intel DX4-100.
The reason for delaying it's availabilty is clear, Intel wanted customers to buy their Pentium 60 and 66 systems. Except floating point intensive application, the Pentium 60 would have had a hard live against the DX4-100.

But yes, all what I wrote it is about DX4-100, DX4-75 was released together with the 100. It never made much sense from the very beginning, because of the low FSB, 25MHz is just not good for a 486.
Off-topic:
On a desktop PC, one could set it to 40MHz bus and multiplier 2, that will be a lot faster. I think it can handle the 40MHz internally. For sure it will beat then all Cyrix and AMDs DX2-80, because of the 16kb L1 cache.

the idea I got is that the DX4 75 only makes sense as an overdrive of very slow 486 sx25s. Building a system from scratch that is designed for this CPU means saving a few dollars to build it but giving the buyer a much slower system. It is where we glimpse the desire to earn money at the expense of everything and everyone. Anyway, returning to the topic, this is the photo of the CPU, it is mounted on a strange board that also includes (not present) memory chips...

It's close to the monitor connectors but I think it's the CPU because that thermal pad makes contact with the cover that has been disassembled which in turn is metal and seems to act as a large passive heat sink, why dissipate a graphics chip instead of the CPU? so I assumed it was the CPU

Played with two of those, both worked fine at 33MHz fsb with same small laptop non cooling solutions.
Intel didnt want to sell cheaper Pentiums, but market needed cheap CPU thus DX4 in both desktops and laptops took over the role of 386SX.
Imo it was never a good idea to buy into those Intel low end alternatives until Mendocino Celeron, skipping P4 Celerons and again with great value Core2 Celerons and Haswell Pentiums. Used server market took over as the best source of cheap base components around 2017. Why buy i7-4770 or whatever 4Core Intel CPU of the day when decommissioned (3 year cycle) 1150 Xeons E3-1286v3 flooded the market at a fraction of cost killing it at value/$. Thankfully now with once again viable AMD Intel is no longer selling turd sandwiches for the most part, and even a lowly ~$100 i3-14100F is solid entry level.