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486 Overdrive, questions.

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RaptorZX3

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Ok my Packard Bell Legend 125 have an Overdrive socket on the board (blue socket with latch), but i checked on Wikipedia, and they said they made 2 types of sockets with different amount of pins.

This computer have a 486SX 25Mhz (don't know the FSB speed though), and i would like to boost it up to around DX 33Mhz or 66Mhz. But then i don't know which one would work on this computer.



Can someone help me please with the pins number? and which one would be good for this computer? thanks.
 
I think I remember reading that Wikipedia blurb at some point and finding it pretty confusing. Sometimes Wiki works, sometimes it doesn't... The OverDrive options are actually pretty straightforward, and there's an Intel datasheet that explains everything very clearly. (Available at datasheets.chipdb.org/Intel/x86/486/applnots/29043606.pdf, among other places.)

There were two types of i486 upgrade OverDrive processors: the DX2's, which doubled the clock speed of the processor core, cache, etc., relative to the external bus, and the DX4's, which tripled it. Both types were packaged as either 168-lead PGAs or 169-lead PGAs. The 168-pin OverDrive processors were for single-socket systems and actually replaced the existing 486 (usually DX) processor. The 169-pin package was for systems with two sockets: The OverDrive processor was installed in the second socket, and the original processor remained in place. The extra pin was actually a key to prevent users from inserting the OverDrive chip the wrong way. (>.<)

So in your case, since you have the second socket, you would want the 169-pin package. (In Intel's product codes for the OverDrive processors, 169-pin PGAs are denoted "ODP" and 168-pin packages are labeled "ODPR." I've always figured the "R" must mean "replacement," since the 168-pin OD's take the place of the existing processor.) With a 486SX at 25MHz, in principle your options are to install either a DX2ODP50 (DX2 => clock-doubled, ODP => 169 pins, 50 => 50MHz internal processor clock speed) or a DX4ODP75 (clock-tripled to 75MHz). I looked at Intel's OverDrive support website to try to verify your system's compatibility, but as luck would have it, although there's a document called "System Compatibility List, A-O," there's no corresponding document for the remainder of the alphabet! Since you have a second socket, it seems reasonable to assume that your system will recognize the OverDrive processor, but... In any event, if you know what type of motherboard you have, you should be able to verify its compatibility pretty easily.
 
in fact the processor is NOT in a socket, it's embedded on the motherboard, does it still count as a "socket" since the CPU is still there?

Edit: wow, those 2 Overdrive CPUs are expensive! and most of the time untested...guess it's for the quantity of gold in them? Maybe i could try to trade my Pentium Pro 200Mhz 512kb cache CPU since i don't have anything to use it here?
 
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There isn't that much gold. They're silicon chips, not gold chips - it's mostly plastic and glorified sand in there :) The tiny amount of gold you might find isn't really worth much, but people get excited about it. The prices will just be people trying to get as much as they can - you may have to wait for a good deal if you don't spot something.

Overdrive chips should automatically disable your soldered in CPU. Just make sure you get the right type as per post above :)
 
There isn't that much gold. They're silicon chips, not gold chips - it's mostly plastic and glorified sand in there
Click to expand...
LOL! But in Intel's defense, it's glorified quartzy sand. oooooh. :wow:
 
So in your case, since you have the second socket, you would want the 169-pin package.
Click to expand...

Or a 168 pin one. You can use a standard 486 chip in those sockets, as long as you're mindful of the orientation.

Years ago, I ran a regular non-Overdrive DX2/66 in my PB (which I believe was actually a Legend 125, or at least a very similar model). I don't recall the upgraded CPU being autodetected... I'm pretty sure there were some jumpers that had to be changed to set the CPU type and bus speed, but in any case, it worked. And regular DX2 chips should be pretty cheap to get, though you'd also need to be sure to get a heatsink to go with it.
 
I don't know your board, but there were many 486 boards (with one socket, two sockets or one socket + one soldered CPU) which could be upgraded with a regular (non-overdrive) 486. It depends on how the original CPU is attached to the board and on which jumpers it has (for example: one jumper to disable the soldered CPU, some jumpers to change the clock frequency...)

If there's a socket with latch (as you said) it's also highly probable that you can upgrade it with a Pentium Overdrive, too. There are 2 which could be used: 63 and 83 MHz (25x2.5 and 33x2.5). Pentium overdrives with other speeds will not work in your 486 board, as they are designed for different sockets. But the Pentium Overdrive is expensive, too.
 
And of course you've also got the "586" upgrade chips from Kingston, Hypertech et el. There use to be a geocities pages dedicated to PB x86 systems with owners listing their upgrades. I'd imagine bits of the site are still available. IIRC there's a. UK based one as well which I'm sure has been linked to here in the past. It had all the various mobos jumper sttings etc..
 
it's an embedded/soldered CPU on the motherboard, with the blue 486 Overdrive socket nearby which is located on the side where the ISA cards go (this computer have an ISA 3-slots riser card), but yes i think there are jumpers to set up the bus and speed, but i didn't touched those.
 
If the original CPU is soldered and there's no jumper to disable it, you can only install an overdrive CPU (probably just a 169-pin overdrive, as stated in message #2). Probably also a 487 (hard to find, and it will not speed up a lot).

But if there's a jumper to disable it, you can use any 486 CPU. For example, I have a board with a 25 MHz 486SX soldered and a socket where I installed a 66 MHz 486DX2 (a regular one, not an overdrive).

Anyway it is good to have jumpers to set clock, because your new CPU (regular or overdrive) will not be limited to 25 MHz x 2 or 25 MHz x 3.

Do you have a manual for your board? If not, take a look here. Is it your board? If it is, there's a list for CPUs and speeds that you can use. The P24T is the Pentium Overdrive I told you.

BTW, your socket is for 168, 169, 237 or 238 pins? (just to make sure)
 
the board have 1 memory bank, support up to 20mb (3mb on-board, added a 16mb EDO on it), i don't know about the Overdrive pins count, but the socket is blue and it says "Intel Overdrive Ready" on it, there are 3 square corners and 1 edged corner.

I opened it not long ago to scrub with cotton swabs around where the battery was located to clean it up to remove as much acid as possible just to make sure, and the board sure is dirty...like it was kept somewhere with a lot of cigarette smoke, anyway i tried to clean it so it wouldn't get damaged with battery acid anymore, and cleaned some air intake of the PSU...

"PY4307-04" is written on the edge of the board near where the battery was located. With a quick look, some sites say it's a "Socket 2" on it. There are 4 rows of pins on each side, with a corner being edged, and a pin hole on the inside, probably some kind of keyed pin so we wouldn't insert it the wrong way or something.

It look like this one here, but mine is still blue, but written "Intel Overdrive Ready" in the middle:
https://en.wikipedia.org/wiki/Socket_2#mediaviewer/File:Intel_Socket_2_ZIF_CPU_socket_for_486_and_Pentium_Processors.jpg
 
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Aha, I just wanted to confirm if a Pentium Overdrive can be used. Until yesterday I would say that it can be used only in sockets 2 & 3... but I have just read that unofficially it also runs in socket 1 (read this thread if interested on it) even with some pins on air.

With the 83 MHz Pentium Overdrive you would advance one generation, multiply your current MHz, and have an FPU. All three things should be noticed.
 
so which CPU should i look for? there seem to be many kinds...i checked for the Pentium Overdrive 83Mhz, and it says it's to upgrade a 486SX/DX 33Mhz or Intel DX2 66Mhz...or is the 33Mhz irrelevant for the upgrade?
 
The Pentium Overdrive 83Mhz, will run at external bus speed x 2.5

If your 486SX is running at 25 MHz and you plug a P.O. 83 it will run at 63 MHz (25 x 2.5)

If you change jumpers to select 33 MHz bus speed and you plug a P.O. 83 it will run at 83 MHz (33 x 2.5)

The Pentium Overdrive 63MHz will also run at external bus speed x 2.5 but will support only 25 x 2.5

If you don't know how to set jumpers for 33 MHz, get a 63 MHz part.
 
The problem of changing speed is heat dissipation. Slower external bus frequency and/or lower multiplier means less heat, so it is safe. Even the Pentium Overdrive itself, reduces MHz (uses multiplier x1) when the fan doesn't work.

But, can't you find anybody else who has the same board (to tell you how to change bus frequency)? It's strange...
 
maybe LGR (Phreakindee) could help me? i don't know, but if the CPU is 25Mhz...i think the bus speed would be 25Mhz too...maybe?
 
Rauli said:
The Pentium Overdrive 83Mhz, will run at external bus speed x 2.5

If your 486SX is running at 25 MHz and you plug a P.O. 83 it will run at 63 MHz (25 x 2.5)

If you change jumpers to select 33 MHz bus speed and you plug a P.O. 83 it will run at 83 MHz (33 x 2.5)

The Pentium Overdrive 63MHz will also run at external bus speed x 2.5 but will support only 25 x 2.5

If you don't know how to set jumpers for 33 MHz, get a 63 MHz part.
Click to expand...

Yeah, if there is a jumper to change the BUS speed from 25 to 33 MHz, you do that, even if you don't change the CPU. Almost every 486SX-25 can work fine at 33 MHz. My 486SX-25 board from IBM has no jumper to set the clock and the only option is to change the 50MHz oscillator to an 66MHz one.
 
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