Well, technically it's P200 MMX with the locked 2.5x or 3x multiplier, the power converter and the built-fan (so it uses +3.3V rails only and works in Socket 5 motherboards).
IIRC there are 4 processors in this "Pentium Overdrive MMX" line, 150/166/180/200 MHz. PODPMT66X200 is the rarest.
And the old "1X multiplier w/o the fan" behavior is still here. 😀

Yep, forgot to include the MMX part. 😀 Figures the one I want is the rarest. 🤣.

If you want to save money get a regular P233 MMX, they handle 3.3V just fine as long as you use a heatsink that can handle a K6. You get 33 extra MHz and I even think the motherboard is better off without the hot running little overdrive with its tiny heatsink.

Im pretty sure the extra power the Pentium MMX needs at 3.3V isnt more than the Overdrives VRM loses when transforming 3.3V to 2.8V. When using either an Overdrive or a regular Pentium MMX with an old Socket-5 board be sure you got some airflow in the case.

edit -o

Skyscraper wrote:

If you want to save money get a regular P233 MMX, they handle 3.3V just fine as long as you use a heatsink that can handle a K6. You get 33 extra MHz and I even think the motherboard is better off without the hot running little overdrive with its tiny heatsink.

Im pretty sure the extra power the Pentium MMX needs at 3.3V isnt more than the Overdrives VRM looses when transforming 3.3V to 2.8V. When using either an Overdrive or a regular Pentium MMX with an old Socket-5 board be sure you got some airflow in the case.

I'm not sure that would work in my motherboard. It lists cpu support as 75-133Mhz, with special jumper configs for Overdrive processors up to 200Mhz.

clueless1 wrote:

Skyscraper wrote:

If you want to save money get a regular P233 MMX, they handle 3.3V just fine as long as you use a heatsink that can handle a K6. You get 33 extra MHz and I even think the motherboard is better off without the hot running little overdrive with its tiny heatsink.

Im pretty sure the extra power the Pentium MMX needs at 3.3V isnt more than the Overdrives VRM looses when transforming 3.3V to 2.8V. When using either an Overdrive or a regular Pentium MMX with an old Socket-5 board be sure you got some airflow in the case.

I'm not sure that would work in my motherboard. It lists cpu support as 75-133Mhz, with special jumper configs for Overdrive processors up to 200Mhz.

The Pentium MMX 233 use the same jumper settings as the P100, it should™ work.

If you already have a Pentium MMX 166 or 200 CPU you can always try one of those before buying a 233 MHz model, they should™ all work at 133 MHz with the same jumper settngs as a normal P133.

There is one case when a Pentium MMX is not a good choice and that is when a Socket-5/7 motherboard only support 3.5-3-6V (VRE) and not 3.3-3.4V (STD) as 3.6V is right on the limit of what a Pentium MMX chip can handle (3.7V absolute Vmax according to the spec).

But do we know if his motherboard supports spilt votage rails necessary for the Pentium MMX, early socket 7 boards did not.

candle_86 wrote:

But do we know if his motherboard supports spilt votage rails necessary for the Pentium MMX, early socket 7 boards did not.

The Pentium MMX do not need split voltage rails to function, it will run on a 3.3V Core/IO "STD" voltage spec just fine, at least on the motherboards I have tried but the "VRE" 3.5V-3.6V voltage spec is a bit too high for me to think its a good idea.

Overvolting do increase the power draw though but I bet a Pentium MMX 233 @ 3.3V still isnt worse than a stock K6 233 MHz (3.2V). Intel did not push the Pentium MMX because they diddnt have to.

If one really wants to play it safe neither a fast Overdrive with its own VRM or overvolting a Pentium MMX CPU is a good idea for an old Socket 5 motherboard. The point is that Im not sure one is worse than the other as I think both will draw about the same amount of power because of the power loss in the Overdrives VRM. What I am sure of is that it's easier to find a good cooling solution for the Pentium MMX that also cools the motherboard area around the CPU.

The Pentium MMX 166 and Pentium MMX 200 do not always support the 1.5x = 3.5x multiplier which can be an issue on old boards with only a single jumper for multipliers (1.5x and 2x).

Skyscraper wrote:

The Pentium MMX do not need split voltage rails to function

Dunno.
IIRC the chip uses the same 296-pin package as classic Pentiums. Minus 11 E pins (E11-E31), minus 13 AJ pins (AJ7-AJ31) and AH32 pin isn't used too so it can be inserted in the Socket5 w/o any trouble.
But use MMX's w/o the correct dual VRM... Not see the point to do this. Overclocking and overvolting is a serious disease. 😀

The motherboard I'm considering this for has official support for Overdrive processors up to 200Mhz, so I don't anticipate compatibility issues there. I've also read reports of people using a 233MMX and K6-2 with a Powerleap adapter. Here's more info on the motherboard:
http://www.uktsupport.co.uk/pb/mb/570.htm

Gamecollector wrote:

Dunno. IIRC the chip uses the same 296-pin package as classic Pentiums. Minus 11 E pins (E11-E31), minus 13 AJ pins (AJ7-AJ31) a […]
Show full quote

Skyscraper wrote:

The Pentium MMX do not need split voltage rails to function

Dunno.
IIRC the chip uses the same 296-pin package as classic Pentiums. Minus 11 E pins (E11-E31), minus 13 AJ pins (AJ7-AJ31) and AH32 pin isn't used too so it can be inserted in the Socket5 w/o any trouble.
But use MMX's w/o the correct dual VRM... Not see the point to do this. Overclocking and overvolting is a serious disease. 😀

Some poeple see it that way, Im just saying that isnt isnt sure that a Pentium MMX Overdrive is a better option if one has the wellbeeing of the motherboard in mind. To the motherboard the current drawn is what creates heat and therefor what is dangerous.

For example a 0.18 micron Cyrix MII CPU rated at 2.2V is pushed just as hard as a 0.28 micron Pentium MMX CPU overvolted at 3.3V. Intel never needed to push their CPUs close to the limit as they led the performance race anyhow.

I see both the Overdrives and overvolting of retro CPUs as something one uses/does for benchmarks and tests. For retro rigs used for everyday gaming a motherboard meant for the CPU in question is always better than both overvolted Pentium MMX CPUs and Overdrives on older boards.

clueless1 wrote:

The motherboard I'm considering this for has official support for Overdrive processors up to 200Mhz, so I don't anticipate compatibility issues there. I've also read reports of people using a 233MMX and K6-2 with a Powerleap adapter. Here's more info on the motherboard:
http://www.uktsupport.co.uk/pb/mb/570.htm

At least your motherboard supports both 3.3V (STD) and 3.5V (VRE). 😀

given the age of the MMX chips these days, id avoid over volting them, and use them only within specs, so given that id go with the POD if its supported, there is a reason they offically support the POD and not the MMX and likely the lack of split rail voltage. Just my two cents, but I'd hate for you to find your MMX degraded after a year or two from being over spec to long.

candle_86 wrote:

given the age of the MMX chips these days, id avoid over volting them, and use them only within specs, so given that id go with the POD if its supported, there is a reason they offically support the POD and not the MMX and likely the lack of split rail voltage. Just my two cents, but I'd hate for you to find your MMX degraded after a year or two from being over spec to long.

If one care about the CPU you have a point but a Pentium 233 MMX is dirt cheap while the Overdrives are rare and expensive.

I have never managed to kill or degrade a Pentium MMX (I own 50+) and I have done unspeakable things to them. My worry is always the motherboards.

So if I wanted to try a 233MMX, I'd set the voltage jumper to VRE and the multipler jumpers to Pentium 100? I probably won't do it, but I wanted to understand the process. MMX processors require VRE?

clueless1 wrote:

So if I wanted to try a 233MMX, I'd set the voltage jumper to VRE and the multipler jumpers to Pentium 100? I probably won't do it, but I wanted to understand the process. MMX processors require VRE?

I just checked your motherboard manaul again and the voltage settings are only marked VR "Voltage Regulated" and VRE "Voltage Regulated Extension". VR is probably 3.3V and the setting to use but if you have a DMM it would not hurt to measure the voltage to be 100% sure it isnt too high. Any voltage over 3.4V would make me uneasy using a Pentium MMX for anything but some short benchmarks and anything over 3.5V is a no go.

If you ask Intel the VRE "Voltage Regulated Extension" is specified to 3.4V - 3.6V and the STD "Standard" is ~3.3V but can be everything from 3.1V to 3.6V and still be within the specification. When I have measuered with a DMM the "STD" voltage setting has always been very close to 3.3V. I prefer when the voltage settings are marked with the actual voltages as motherboard manufacturers sometimes use abbreviations different from how Intel uses them.

And yes the 1.5x multiplier.