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Old 11-17-2019, 05:15 PM   #41
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Default Re: Topcat's Weird Pentium Pro Builds

Laying the groundwork for Build # 2. This one will be a little ongoing, as I'm in search of some Overdrive CPU's that fit the Socket-8....but they're harder to find and pricey. This board already has a pair of 200MHz 512k L2 CPU's that OC to 233 just fine.....but I've already got a Pentium Pro system with those specs, which you already know if you've followed this thread....so I've got to be even more unique for extra cool points! The Overdrive 333's pop up regularly on ebay, but go for $200-ish (I need 2)....I'm not spending that much, so I'll search & scour and I'm sure eventually find a pair cheaper than that! They're basically Pentium2 333's with full speed L2 caches & MMX instruction sets...and of course the infamous Pentium Pro FPU bug fixed. I want to run Win2k and some other stuff on this one, unlike the other running NT4. A pair of 333MHz CPU's, 512mb RAM, and a good GPU will run Win2k very smoothly!

The above said, I had to conquer the first hurdle....a case that can handle this board. It's a primative eATX, I think it was originally intended for some proprietary Intel server case, given the way it's 'notched'...but by modern standards, its basically an eATX. I wasn't going to waste a high-end modern Supermicro eATX case on this....but I did have an Enlight beige case that looked like it might be a match. It was housing a VP6, but a VP6 will fit in anything, so I stripped it out. It was also the lab rat for the bromine yellowing removal experiment, and it held up well! The case isn't 'officially' an eATX, because of the 5.25" cage; a REAL eATX board would not clear the cage at all...but the lower half has all the appropriate motherboard mount points for an eATX board...the 'notch' of this board saved the day! The board fits this case like a glove, and NOTHING had to be modified! Every mount point on the board has the correct corresponding mount point on the case backplane, and it clears everything....albeit, close in a few places....but get a load of this!!





Wow, now how was that for awesome fitment!!

Now for the goofy non-standard IO shield.....which I don't have, and after a year of looking I haven't found one....so....hmmmm



I'm going to have to attempt to ratdude one from a blank....I got 4 of them so when I completely hose one I've got spares, they're cheap....Missing IO shields are one of my biggest pet-peeves.....it makes the system look so shoddy & incomplete.



Test fitting with drives in place....

Opticals clear the board in the corner by ~2mm.....Fanned HDD holder clears by more than plenty.







Now the lower fan holder & 3.5" cage....all clear! There's a good inch between the board and the 3.5" cage, ribbons may be a little tight in there, but it's no biggie. There will be no IDE devices in this system, it'll all be SCSI. The only ribbon that will be connected there will be for the floppy, and it'll clear by plenty. The fan holder isn't a clearance factor at all.







This will be a fun one!!
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Old 11-18-2019, 03:57 PM   #42
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Default Re: Topcat's Weird Pentium Pro Builds

This stuff is epic. I'm not sure I was even born when this spec was released.
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Old 11-18-2019, 06:25 PM   #43
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Default Re: Topcat's Weird Pentium Pro Builds

Quote:
Originally Posted by Gergely_madbad View Post
This stuff is epic. I'm not sure I was even born when this spec was released.
This stuff is all circa mid-1990's; 1996 give or take a year...

Ok, first attempt at the IO shield, free-handing with a dremel....

Marked, using some random IO shield for port patterns, that were measured off the actual board.



...and afterward.... Fitted outside the case....things lined up good....but in the case may tell a different story....



Nope, still lined up!!





Not sure if I'm going to take another crack at it to 'clean it up' a little....it's not perfect (and no hand-made IO shield ever will be).....but it came out pretty darn good!
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Old 11-19-2019, 01:03 PM   #44
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Default Re: Topcat's Weird Pentium Pro Builds

Maybe someone should make a website that has paper templates for all the ATX IO shields for every motherboard out there... then if you need one, download and use that to cut...
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Old 11-19-2019, 06:29 PM   #45
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Default Re: Topcat's Weird Pentium Pro Builds

A little today...I'm limited as to what I can do....I don't have a good GPU for this system, my selection of PCI video cards is limited pretty much to junk....so I'll have to look around...and I still haven't found the CPU's I want....but I did begin a little assembly & testing....

I opted not to attempt a second IO shield, the first one did just fine.


Motherboard mounted and a test mockup set. The test GPU is a 512k Matrox Millennium....weaksauce! The IDE drives are just temporary.





Installing Win2k.


The permanent drives (not yet installed). I need to find some more Enlight drive rails, I'm out of them it seems... The drives are a pair of 18gb 15k RPM Cheetah's.


More later....
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Old 11-19-2019, 07:36 PM   #46
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Default Re: Topcat's Weird Pentium Pro Builds

Quote:
Originally Posted by Topcat View Post
Laying the groundwork for Build # 2.
...
The case isn't 'officially' an eATX, because of the 5.25" cage; a REAL eATX board would not clear the cage at all...but the lower half has all the appropriate motherboard mount points for an eATX board...the 'notch' of this board saved the day! The board fits this case like a glove, and NOTHING had to be modified! Every mount point on the board has the correct corresponding mount point on the case backplane, and it clears everything....albeit, close in a few places....but get a load of this!!

https://www.badcaps.net/forum/attach...1&d=1574031618

https://www.badcaps.net/forum/attach...1&d=1574031618

Wow, now how was that for awesome fitment!!
Noice!!!
Don't you just love it when you have a bunch of "random" parts for a project that all by coincidence happen to fit together perfectly?

It's like that motherboard you had was made exactly for that case... or the other way around. Either way, that looks like it will be its permanent home, I'm betting.

Quote:
Originally Posted by Topcat View Post
Now for the goofy non-standard IO shield.....which I don't have, and after a year of looking I haven't found one....so....hmmmm
...
I'm going to have to attempt to ratdude one from a blank....I got 4 of them so when I completely hose one I've got spares, they're cheap....Missing IO shields are one of my biggest pet-peeves.....it makes the system look so shoddy & incomplete.
Lol. Most of my PCs are missing the IO shield. Actually, for many of them, I have the IO shield, but I never installed it simply to allow for "extra cooling" on some of my builds.

The only times I regret not installing IO shields is when I try to plug stuff on the back of the computer without looking (typically due to not being able to move the PC or access its back easily.) In these cases, the IO shield helps me guide my hand to find the ports.

Quote:
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This will be a fun one!!
No doubt.

Quote:
Originally Posted by Topcat View Post
The permanent drives (not yet installed). I need to find some more Enlight drive rails, I'm out of them it seems... The drives are a pair of 18gb 15k RPM Cheetah's.
Cool.
Those should be plenty fast for that system. Maybe even over the top, but why not. I do have some more "era-appropriate" SCSI drives that I am planning on sending your way. Probably not the fastest things in the world, but might be good for their "cool" factor? I just cleaned/zero'd two more SCA drives last weekend. Now I need do the same with the 50-pin SCSI drives. Don't know if I have the right hardware, though.

Quote:
Originally Posted by Topcat View Post
I do have a 15" 4:3 LCD here, but its ancient and hideous to look at.
Yeah, same here.
On mine, the panel still works just fine (1024x768 resolution max ), but the backlights are shot. This thing ran 24/7 for 10+ years, as far as I know. The CCFLs were so worn out that the entire image was barely visible and all orange-pink hued. If I replace the backlights with LEDs, it should still be good for another 15-20 years, given how the rest of it is build. But I don't know if/when that will be. It's one of those super-old LCDs that is not quite so "slim" and actually weights quite a bit - less than a CRT of equivalent screen size, but not that much less (maybe half at best, LOL.) Good reliable equipment, but way too outdated.

Quote:
Originally Posted by Topcat View Post
That just hurt my soul a little..... :-/
Well, some good news regarding that...
Turns out, those PCI and ISA cards that I thought were SCSI, are NOT that - AT ALL!
Unfortunately, I had to find this the hard way: plugged one into a test PC of mine, then connected an HDD to it with a 50-pin cable.
Results: SMOKE!!

I always set up my test PC so that I'm near its power plug, though. So I was able to unplug the PC within seconds. This was still enough time to melt a few wires in the 50-pin cable. But luckily, that is all that seems to have been damaged. The HDD I tested this with appears to spin up and do a self-test just fine, though. Probably survived, but can't tell until I have the right hardware to test it out for sure.

Nevertheless.... Ooops!

At least my bench has a "proper" electronics smell now.

Last edited by momaka; 11-19-2019 at 07:42 PM..
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Old 11-26-2019, 05:45 PM   #47
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Default Re: Topcat's Weird Pentium Pro Builds

Diddled around with this a little today...... Notice something awesome that's filling the formerly empty PCI slot?

I spent $10 on ebay and grabbed a Matrox G450 PCI....those are very close to period-specific and were great 2D cards for the time. 3D will be handled by the mystery card under it.



Atleast now I can have it in True Color above 800x600! MUUUUCH BETER!



Things just kind of sitting...and what it'll look like when assembled. I still haven't grabbed any enlight drive rails yet, the bottom 2 drive trays are just sitting in there....the rails are ~$10/pr on ebay.



More later!
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Old 12-03-2019, 07:00 PM   #48
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Default Re: Topcat's Weird Pentium Pro Builds

I really like the progress there.

The case looks really nice!
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Old 12-03-2019, 10:26 PM   #49
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Default Re: Topcat's Weird Pentium Pro Builds

IIRC, from the horses mouth, (Intel) the floating point bug only exists in Pentium 100s and earlier, except for possibly the 120s.

Looks like it was fixed by the time the 133 consumer chips came out.
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Old 12-07-2019, 09:26 AM   #50
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Default Re: Topcat's Weird Pentium Pro Builds

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IIRC, from the horses mouth, (Intel) the floating point bug only exists in Pentium 100s and earlier, except for possibly the 120s.

Looks like it was fixed by the time the 133 consumer chips came out.
There was a different FPU bug that affected the p-pro.

Quote:
After the microprocessor was released, a bug was discovered in the floating point unit, commonly called the "Pentium Pro and Pentium II FPU bug" and by Intel as the "flag erratum". The bug occurs under some circumstances during floating point-to-integer conversion when the floating point number won't fit into the smaller integer format, causing the FPU to deviate from its documented behaviour. The bug is considered to be minor and occurs under such special circumstances that very few, if any, software programs are affected.

The Pentium Pro P6 microarchitecture was used in one form or another by Intel for more than a decade. The pipeline would scale from its initial 150 MHz start, all the way up to 1.4 GHz with the "Tualatin" Pentium III. The design's various traits would continue after that in the derivative core called "Banias" in Pentium M and Intel Core (Yonah), which itself would evolve into the Core microarchitecture (Core 2 processor) in 2006 and onward.[8]
https://en.wikipedia.org/wiki/Pentium_Pro

I think I may have found a pair of Overdrives.....still working on it though.
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Old Yesterday, 02:13 PM   #51
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Default Re: Topcat's Weird Pentium Pro Builds

Did some more diddling around, found a spec sheet that Intel never published for this board with some 'undocumented jumper settings'. First one was the multiplier, which 'officially' only goes to 3.0x. I already found 3.5x on my own, but there's also 4.0x, which allowed the CPU's to run @ 266/66.....but that was a failure, the CPU's were not stable....and I wasn't really expecting them to be. Historically with the P6 core, 233 was about as high as they would ever run stable.

The second one was a FSB tweak, which allows 60FSB bumped to 63, and 66FSB bumped to 70....it's basically an undocumented 'turbo' function....which from 3.5x @ 70FSB, the CPU's are @ 245MHz, which was also unstable.....but the golden ticket will be the overdrive 333's, which are locked @ 5.0x multipler, so changing that won't affect anything....but hey, it *might* run @ 350/70FSB. Yea, nothing to get overly excited about....but it's still fun to tinker with stuff even the manufacturer didn't tell you about!
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Old Yesterday, 05:54 PM   #52
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Default Re: Topcat's Weird Pentium Pro Builds

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Did some more diddling around, found a spec sheet that Intel never published for this board with some 'undocumented jumper settings'. First one was the multiplier, which 'officially' only goes to 3.0x. I already found 3.5x on my own, but there's also 4.0x, which allowed the CPU's to run @ 266/66.....but that was a failure, the CPU's were not stable....and I wasn't really expecting them to be. Historically with the P6 core, 233 was about as high as they would ever run stable.

The second one was a FSB tweak, which allows 60FSB bumped to 63, and 66FSB bumped to 70....it's basically an undocumented 'turbo' function....which from 3.5x @ 70FSB, the CPU's are @ 245MHz, which was also unstable
Did you test them with Prime95? It's easy to think they're stable when not using Prime95 then when the Prime95 test is running, boom! An error is scrolled or you get a Windows error or it just crashes (hard freezes)

SuperPi apparently would be a joke, because it probably can't reveal core instability the way Prime95 and of course, Linpack does!

But there's a good chance that Linpack isn't compatible at all with an old school Pentium.

But, usually, if Prime95 fails, you shouldn't panic and just raise the Vcore a bit and make sure the core temps aren't high. But, you will need to make a thermometer mounting place for the CPUs. Otherwise, you possibly just need to make do with something like 61x3.5.
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Old Yesterday, 08:20 PM   #53
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Default Re: Topcat's Weird Pentium Pro Builds

VCORE is not adjustable on these.

I never got to the point of running prime95....the OS was never stable enough to worry about it. It will be fun to play with the overdrives though. Digging through some really old archives, these boards love them!
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