Installed the Pentium Pro in the case and giving it a stress test currently. Going to loop graphics demos for an hour or so and see how warm the heatsink gets.

Blow across method works very well. Provide some duct to channel the air right at the heatsink best.

Cheers,

Ducting is a good idea. I can fabricate something out of acrylic if need be.

FWIW, I tested this setup for over an hour. Installed all the intended cards, closed up the case and then ran various demos and games.

The heatsink did warm up, but not unbearably so. I could easily keep my hand pressed on it without it getting too hot.

The 80mm fan seems to be providing enough airflow to keep things relatively cool.

I think only the 1mb Pentium Pro runs hot, I would think a case fan like you have setup would be ok.

Yeah, this is the 512kb cache version with a TDW of 36.6W. The 1 MB has a TDW of 47W, so I can see it requiring a direct fan on the heatsink.

FWIW, I also tested the Pentium 200 for an hour and it remained relatively cool overall. So no worries about that one.

Your Pentium 1 heatsink is already pretty large (compared to the stock/OEM one), so a bit of airflow should be heaps.

mwdmeyer wrote on 2023-12-04, 02:12:

I think only the 1mb Pentium Pro runs hot, I would think a case fan like you have setup would be ok.

Pretty sure it runs hot due to Intel removing the gold heat spreader used in the earlier models 🙁 Shame as I honestly prefer the golden look.

Trashbytes wrote on 2023-12-04, 05:52:

mwdmeyer wrote on 2023-12-04, 02:12:

I think only the 1mb Pentium Pro runs hot, I would think a case fan like you have setup would be ok.

Pretty sure it runs hot due to Intel removing the gold heat spreader used in the earlier models 🙁 Shame as I honestly prefer the golden look.

I did do a quick google. Seems even 36.6W would need a big heatsink for passive cooling, so while I think fine, a fan near the CPU with good airflow is important.

mwdmeyer wrote on 2023-12-04, 06:05:

Trashbytes wrote on 2023-12-04, 05:52:

mwdmeyer wrote on 2023-12-04, 02:12:

I think only the 1mb Pentium Pro runs hot, I would think a case fan like you have setup would be ok.

Pretty sure it runs hot due to Intel removing the gold heat spreader used in the earlier models 🙁 Shame as I honestly prefer the golden look.

I did do a quick google. Seems even 36.6W would need a big heatsink for passive cooling, so while I think fine, a fan near the CPU with good airflow is important.

Yeah, I have a Pentium Pro Overdrive build myself but the Original PPro CPU it had was a 512k model and it came with a big heatsink but its fan was actually the fan in the power supply, it had a plastic shroud that allowed the PSU fan to pull the hot air out through the PSU.

The PPro Overdrive though has a heatsink and fan attached but its not that big, I guess the PII Overdrive core runs cooler than the 1Mb CPUs. I think you could get away with some good case airflow and a big passive heatsink, you can get some really good high CFM fans from noctua that wouldn't look odd in a retro build. (I personally dont use old fans, they are inefficient compared to new stuff from noctua and normally dont live long after sitting unused for many years)

Looking at the pic of how its setup in the case it should be ok, could even fashion a acrylic shroud that directs the air to the CPU cooler.

I’ve got a few of the overdrive chips but no fan. Can’t find tdp for them but would be very interested to know!

I would definately mock-up some kind of duct. I've had succes using card board and - well - duct tape earlier ... Just to point flow the right direction.

mwdmeyer wrote on 2023-12-04, 06:41:

I’ve got a few of the overdrive chips but no fan. Can’t find tdp for them but would be very interested to know!

Looking at wiki it lists the Pentium II 333 at 20.6w @ 2.0v so Im guessing the PPOD 333 is rated a bit higher since its got 512k of cache at full CPU speed and runs at 3.3v. (Im guessing closer to 45 watts TDP)

Really hard to compare the PPOD to a normal PII since its a Xeon core rather than a normal PII.

Pentium 200 will require active cooling on that motherboard. The radiator is sitting very closely to linear voltage regulators.

The Serpent Rider wrote on 2023-12-04, 06:59:

Pentium 200 will require active cooling on that motherboard. The radiator is sitting very closely to linear voltage regulators.

Thats a great point, either active or a shroud to direct airflow over the CPU and voltage circuit.

After seeing Re: Ultimate Annual Gaming Builds: 1994 (P90) and 1995 (P133) I would most definately recommend some shroud as, unless the picture plays tricks on my eyes, it looks like the fan is something like 20 mm "higher" than the motherboard?

H3nrik V! wrote on 2023-12-04, 11:46:

After seeing Re: Ultimate Annual Gaming Builds: 1994 (P90) and 1995 (P133) I would most definately recommend some shroud as, unless the picture plays tricks on my eyes, it looks like the fan is something like 20 mm "higher" than the motherboard?

Closer to 40mm. The top of the heatsink is 35mm from the motherboard.

Here's an interior show betting showing the orientation. The fan doesn't directly blow through the heatsink, but does move air adjacent to it.

I did stress test it for a solid hour and the heatsink got a little warm but not excessively. It didn't even get as warm as the Pentium Pro's heatsink, which has the fan blowing directly through it.

Trashbytes wrote on 2023-12-04, 06:36:

I think you could get away with some good case airflow and a big passive heatsink, you can get some really good high CFM fans from noctua that wouldn't look odd in a retro build.

I was comparing airflow of the various Noctua fans. The 80mm fan do push a lot more air than the smaller ones.

R8 redux-1800 (80mm) - 53 cubic meters per hour
NF-A6x25 FLX (60mm) - 29.2 cubic meters per hour
NF-A4x20 FLX (40mm) - 9.4 cubic meters per hour

mwdmeyer wrote on 2023-12-04, 04:13:

Your Pentium 1 heatsink is already pretty large (compared to the stock/OEM one), so a bit of airflow should be heaps.

This is my thinking too. It's got a lot more area for heat dispersion than a stock heatsink and coupled with a decent amount of adjacent airflow should be enough to keep it cool.

The Serpent Rider wrote on 2023-12-04, 06:59:

Pentium 200 will require active cooling on that motherboard. The radiator is sitting very closely to linear voltage regulators.

Interestingly when I stress tested the system, it seemed like the voltage regulator heatsinks got warmer than the main Pentium heatsink.