I'm certain of the clock speed, but I think you're right that the manufacturers alleged they were fine without additional cooling. (They considered it a bad look, and actually said that chips sold with fans were likely overclocked chips intended for a lower speed bin, or otherwise graymarket.)
But consensus among everyone _but_ the manufacturers was that additional cooling couldn't hurt. (A representative opinion can be found in Upgrading And Repairing PCs, whatever edition was current at the time.) Running right at the top of Tcasemax wasn't good for longevity in terms of electromigration within the chip itself, nor for the capacitors and other components in the neighborhood. Thermal goop wasn't commonplace yet, but the little heatsinks and fans sold like hotcakes (har!) at the local computer shows. Plain aluminum heatsink, clear (polystyrene?) fan, with a holographic "CRYSTAL COOLER" sticker on top. I still see the fans around, but without the shiny sticker.
The Am486DX-40 was my favorite chip. With a VLB video card (Trident 9400CXi) that worked well on the 40MHz bus, its pure pixel-pushing power ran rings around 33MHz-bus systems regardless of their core clock, and that included the P-75. I later got the impression that I lucked out with that Trident card, as almost everyone else with a 40 or 50MHz VLB machine had tales of woe and flakiness.
Thanks for the reply! That is interesting and makes a lot of sense.
Yes, running a 40 or 50 MHz bus made a huge difference, especially if you could get VLB graphics running reliably on it. I'm into collecting and tinkering with 486-era machines for nostalgia's sake and often i see things like DX2 or DX4 systems with plain cheapo 16-bit ISA graphics cards and think such wasted potential...
But consensus among everyone _but_ the manufacturers was that additional cooling couldn't hurt. (A representative opinion can be found in Upgrading And Repairing PCs, whatever edition was current at the time.) Running right at the top of Tcasemax wasn't good for longevity in terms of electromigration within the chip itself, nor for the capacitors and other components in the neighborhood. Thermal goop wasn't commonplace yet, but the little heatsinks and fans sold like hotcakes (har!) at the local computer shows. Plain aluminum heatsink, clear (polystyrene?) fan, with a holographic "CRYSTAL COOLER" sticker on top. I still see the fans around, but without the shiny sticker.
The Am486DX-40 was my favorite chip. With a VLB video card (Trident 9400CXi) that worked well on the 40MHz bus, its pure pixel-pushing power ran rings around 33MHz-bus systems regardless of their core clock, and that included the P-75. I later got the impression that I lucked out with that Trident card, as almost everyone else with a 40 or 50MHz VLB machine had tales of woe and flakiness.
If you're not already familiar with it, you'll likely enjoy this trip down memory lane: https://redhill.net.au/ig.html