First post, by AlessandroB
since the cpu runs at 3.2 volts, theoretically it could work on a socket5 computer? (IBM PC330 P75)
since the cpu runs at 3.2 volts, theoretically it could work on a socket5 computer? (IBM PC330 P75)
No, because it needs dual voltage.
The core can handle 3.3V so I wouldn't worry about dual voltage.
There's a key pin (AH32) on dual voltage CPUs though so without modifications you won't be able to physically fit the CPU into the socket.
Also your BIOS has to support the CPU and the board's VRM have to deliver enough amps to drive the CPU.
It works fine on single voltage but your linear motherboard regulator will burn up in 30 seconds
rmay635703 wrote on 2020-10-02, 16:48:It works fine on single voltage but your linear motherboard regulator will burn up in 30 seconds
I can't say for certain but looking at pictures of the IBM PC330 mainboard online it looks like they used a switching VRM design. (coils, large capacitors, no heatsink on transistor)
Doornkaat wrote on 2020-10-02, 17:01:rmay635703 wrote on 2020-10-02, 16:48:It works fine on single voltage but your linear motherboard regulator will burn up in 30 seconds
I can't say for certain but looking at pictures of the IBM PC330 mainboard online it looks like they used a switching VRM design. (coils, large capacitors, no heatsink on transistor)
Still needs to be rated to about 20 amps, would need to look at the parts
Doornkaat wrote on 2020-10-02, 17:01:rmay635703 wrote on 2020-10-02, 16:48:It works fine on single voltage but your linear motherboard regulator will burn up in 30 seconds
I can't say for certain but looking at pictures of the IBM PC330 mainboard online it looks like they used a switching VRM design. (coils, large capacitors, no heatsink on transistor)
what means that? can probably handle?? and what about bios support?
tnks
AlessandroB wrote on 2020-10-02, 18:05:Doornkaat wrote on 2020-10-02, 17:01:rmay635703 wrote on 2020-10-02, 16:48:It works fine on single voltage but your linear motherboard regulator will burn up in 30 seconds
I can't say for certain but looking at pictures of the IBM PC330 mainboard online it looks like they used a switching VRM design. (coils, large capacitors, no heatsink on transistor)
what means that? can probably handle?? and what about bios support?
tnks
I'd say the likeliness of it being able to handle the CPU is higher than on a linear regulator but nobody can say until they know the circuit and I'm not knowledgeable enough to analyse it.
I also have no idea about BIOS support. I would be a bit surprised if IBM added BIOS support since the CPU does not physically fit the socket without modifications.
But since there are Socket5-7 adaptors maybe either IBM patched their BIOS to support K6 CPUs or somebody else has.
I suggest you go look at BIOS patch notes to find out.
Doornkaat wrote on 2020-10-02, 16:44:The core can handle 3.3V so I wouldn't worry about dual voltage.
There's a key pin (AH32) on dual voltage CPUs though so without modifications you won't be able to physically fit the CPU into the socket.
Also your BIOS has to support the CPU and the board's VRM have to deliver enough amps to drive the CPU.
Yes. The pin is on K6 , but Intel CPUs (incl. MMX) are PGA-296 compatible, so they physically fit even in Socket 5.
I don't think the BIOS has to specifically support CPU. Usually as soon as you satisfy eletric requirements it works. Any BIOS support is just to have proper reporting. There is no microcode update on these CPUs or anything like that.
On the oter hand some Intel OEM boards have provision to only support Intel CPUs, so even K5 won't work.
I succesfully used one of these interposers to fit "S7" CPUs to even very old S5 systems. It has PGA-296 socket on bottom and PGA-321 on top and extra molex connector to less stress the onboard power lines.
so, probably an mmx 233 can work easely? the overvolt i have read is not enough to destroy it. i can try p233mmx with more success??
Easily yes. As the CPU would mechanically fit unlike K6. I wouldn't recommend it through unless you are ready to have it destroyed for the science. Intel explicitly says that no core voltage overshoot is allowed. And I think your motherboard might be more at risk than the CPU...
mpe wrote on 2020-10-02, 21:06:Easily yes. As the CPU would mechanically fit unlike K6. I wouldn't recommend it through unless you are ready to have it destroyed for the science. Intel explicitly says that no core voltage overshoot is allowed. And I think your motherboard might be more at risk than the CPU...
I would also like to add that upgrading the voltage regulator heatsink and maybe adding some airflow across it would be a great idea.
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On the oter hand some Intel OEM boards have provision to only support Intel CPUs, so even K5 won't work.
Based on my experience with S7 boards, Intel most likely will work with AMD CPUs.
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AlessandroB wrote on 2020-10-02, 20:48:so, probably an mmx 233 can work easely? the overvolt i have read is not enough to destroy it. i can try p233mmx with more success??
I don’t think the Pentium 233mmx remapped the 1.5x multiplier to 3.5x and requires split voltage support. I think the easiest upgrade path (and most expensive) would be using a pentium overdrive. With a PODPMT60X180 , you should be able to get to the 180mhz with MMX support.
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AlessandroB wrote on 2020-10-02, 20:48:so, probably an mmx 233 can work easely? the overvolt i have read is not enough to destroy it. i can try p233mmx with more success??
I agree with adding cooling to the regulator. My past experience was that if you overtaxed the regulator things would rapidly become unstable and not become damaged YMMV
Anyway...
At 3.3 volts you might fry the mmx,
Intel MMX chips are much more tolerant of low I/O voltages so a trick back in the day would be to modify your Motherboard voltage regulator To output 2.9-3.1 volts which the MMX should tolerate
(which usually isn’t hard)
You won’t win any overclocking challenges but might get it up and running .
I would start things at 166mhz (if possible) and check stability and move your way up.
Socket 5 only is rated to 5 amps but hopefully IBM overengineered the board to give some headroom for the 6-7 amps the 233 mmx might draw.
Intel MMX chips are much more tolerant of low I/O voltages
3.3v is nothing special for a part working at 2.8v. It will work just fine. Only concern would be quality of voltage regulator.
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