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Pentium Overdrive 83mhz Questions

A

Angry Person

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Aug 20, 2014
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Hi all!

I have recently bought a Pentium Overdrive off Ebay... an 83mhz original for socket 2/3. Having wanted one for a long time I couldn't pass this up. To be honest I've always been interested in the Overdrive 63/83 pentiums, due partly to the features found within the chip.

But anyway, I am having issues with this particular chip on my (only :() socket 3 motherboard - an unknown OPTI based motherboard (with a 237 pin ZIF socket, PCI, ISA, VLB and 256k L2) from the early to mid-nineties. The board has been working with a 486 DX2/66 for a while now, so I figured that the Overdrive would work OK considering it works at a 33mhz bus speed and is able to operate on 5v sockets, like the 486 Overdrives. Yet, when I start the board with the Pentium inside the CPU fan spins up with the PCI IDE card (Promise Ultra33) initializing, but there is NO display at all and NO audible post message from the speaker. When I reinsert the 486... all returns back to normal. I know this could be a simple jumper for the overdrives but I am unsure. What is more annoying is that the CPU jumpers are not silk screened onto the motherboard either!

I have tried removing the RAM and all the I/O cards from the motherboard and no dice; there is still NO beep from the motherboard speaker, which there is if the 486 is inserted. Having no prior experience with 1st gen Pentium Overdrives... I am asking for help in order to understand what the issue is and whether it can be solved or not.

Thanks for reading!
 
Angry Person said:
Hi all!

I have recently bought a Pentium Overdrive off Ebay... an 83mhz original for socket 2/3. Having wanted one for a long time I couldn't pass this up. To be honest I've always been interested in the Overdrive 63/83 pentiums, due partly to the features found within the chip.

But anyway, I am having issues with this particular chip on my (only :() socket 3 motherboard - an unknown OPTI based motherboard (with a 237 pin ZIF socket, PCI, ISA, VLB and 256k L2) from the early to mid-nineties. The board has been working with a 486 DX2/66 for a while now, so I figured that the Overdrive would work OK considering it works at a 33mhz bus speed and is able to operate on 5v sockets, like the 486 Overdrives. Yet, when I start the board with the Pentium inside the CPU fan spins up with the PCI IDE card (Promise Ultra33) initializing, but there is NO display at all and NO audible post message from the speaker. When I reinsert the 486... all returns back to normal. I know this could be a simple jumper for the overdrives but I am unsure. What is more annoying is that the CPU jumpers are not silk screened onto the motherboard either!

I have tried removing the RAM and all the I/O cards from the motherboard and no dice; there is still NO beep from the motherboard speaker, which there is if the 486 is inserted. Having no prior experience with 1st gen Pentium Overdrives... I am asking for help in order to understand what the issue is and whether it can be solved or not.

Thanks for reading!
Click to expand...

The POD 83 is not a slam dunk, so to speak. There were severe comparability issues with some chipsets, while some POD setups even required an interposer. I have a POD 83 and I'm not really a big fan. For one reason or the other, it failed to win me over. I had experienced more than my share of software glitches and stability problems with the POD 83, so I decided to park it some while back . On the other hand, some folks swear by the thing. My favorite 486 platform is a Taiwanese "486-PVT- IO" VLB mobo with an Amx86-P75/AMD-X5-133ADW, from May, 1995. It easily oc's to 150 MHz and runs W95 rather nicely. You are not alone with your problem, as your situation pops up here from time to time. I wish I could be a little more specific as to your immediate problem. One thing comes to mind; can you verify the POD itself? Do you have a way of checking it out on another system?
 
I have a POD 83 myself and it's really just a novelty item in my experience. The only benefit it offers is the Pentium instruction set and a better FPU, so certain games like Quake may run better in some situations. An AMD 5x86 @ 133/160 MHz is a better choice though in my opinion.
 
I remember installing a couple of them "back in the day"...late 90's. Never was that impressed with the end result. But yes, they are a neat footnote in computer history.

Wesley
 
I think the problem comes from the fact that Intel originally specified the so-called P24T upgrade.
Various motherboards were designed with future P24T compatibility in mind.
However, by the time the Pentium Overdrive chips finally surfaced, Intel had changed the specs slightly from the earlier P24T spec.

As a result, there are various boards around that will physically fit a Pentium Overdrive, and their manuals will claim compatibility with a Pentium upgrade chip... but they won't actually work.

My advice is: get a 486 board as late as possible (PCI-based 486 boards are a safer bet in general).
I have a late Compaq Deskpro 466XL machine, and the Pentium 83 Overdrive works like a charm on it.
My earlier board with ALi chipset and VLB doesn't.
 
I currently have one of these up and running. You shouldn't need to mess with the bus speed jumpers coming from a DX2/66, but you might need to switch the voltage jumpers (if your board has any) to 3.3v. I'm not entirely positive (someone please correct me if I'm wrong), but I think the POD 83 actually has to be set for 3.3v and has a built-in voltage regulator that bumps it up to 5v on the chip.

I love my POD, although it gets a bad rap from most people. I wanted a machine that would run most non-3D accelerated DOS games from 1995 until the early 00s and it suits my needs well. Runs stuff like TIE Fighter Collector's CD, Quake (software mode), Wing Commander 3, Duke Nukem 3-D Atomic Edition, and X-Com Apocalypse very well.
 
DamienC said:
I'm not entirely positive (someone please correct me if I'm wrong), but I think the POD 83 actually has to be set for 3.3v and has a built-in voltage regulator that bumps it up to 5v on the chip.
Click to expand...

No, it's the other way around. The CPU runs at 3.3v, but you can use it on a 5v board, where the built-in voltage regulator converts it to 3.3v.

In my Compaq it was as simple as swapping out the 486DX2-66 with the P83OD. I didn't have to change any jumpers or anything. I don't even know if the old 486 was 5v or 3.3v.
 
DamienC said:
(someone please correct me if I'm wrong), but I think the POD 83 actually has to be set for 3.3v and has a built-in voltage regulator that bumps it up to 5v on the chip.
Click to expand...

As mentioned, the CPU voltage has to be set for 5v (few early 486MoBo's had any voltage settings) and the POD's internal voltage regulator drops it down to 3.3v.

https://en.wikipedia.org/wiki/Pentium_OverDrive
 
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