Isn't plugging a 3.45 volt CPU into 5 volted socket a sure way to fry the CPU?

kolmio wrote on 2022-01-31, 16:57:

Isn't plugging a 3.45 volt CPU into 5 volted socket a sure way to fry the CPU?

It's definitely not a good idea, but 486-class CPUs are usually very resilient and will probably work (at least for a while) at 5V.

kolmio wrote on 2022-01-31, 16:57:

Isn't plugging a 3.45 volt CPU into 5 volted socket a sure way to fry the CPU?

I use a Pentium Overdrive PODP5V83 which has its own on-board voltage regulator. It's made for working at 5V.

More stuff I did. Testing a dual sound card setup: Yamaha OPL3-SAx for SB, MIDI and OPL3, and a Primax Soundstorm GUS clone for GUS compatibility. Seems to work fine.

The output of the GUS is connected to line-in on the Yamaha, and the output of the Yamaha to speakers.

The Yamaha card has a Dreamblaster X2 attached. This way I have the best of all worlds. 😀
You can see in the 2nd pic above that the Primax has had its memory upgraded to 1MB.
I've also disabled everything on the Primax except for the GUS synth. No SB emulation, no OPL emulation, no joystick, no useless CD ports.

It's weird that Duke3D doesn't like the GUS to be on an IRQ above 7 and complains about it. I had initially the Primax set to IRQ11 and it was working fine but Duke complained so I moved it to 7. Meh.

I have a Very Similar motherboard with Intel 486dx4-100
See my Post for info and Benchmarks.

Link:
( 1995 ) 486DX4-100, Low budget Win95 “Plug-N-Play” build.

stamasd wrote on 2022-01-31, 18:28:

It's weird that Duke3D doesn't like the GUS to be on an IRQ above 7 and complains about it. I had initially the Primax set to IRQ11 and it was working fine but Duke complained so I moved it to 7. Meh.

Yeah, some games are fine with using higher IRQs for GUS but others (Duke3D and Rise of the Triad come to mind) just refuse to work with IRQ > 7, it's pretty annoying when you have several sound cards in the same PC and need to juggle with all the IRQs.

Grrr and then others like Frontier: First Encounters don't want to work with the GUS unless it's on port 0x220. Which mine isn't (0x220 for Yamaha, 0x240 for GUS).

Intel486dx33 wrote on 2022-01-31, 18:39:

I have a Very Similar motherboard with Intel 486dx4-100 See my Post for info and Benchmarks. […]
Show full quote

I have a Very Similar motherboard with Intel 486dx4-100
See my Post for info and Benchmarks.

Link:
( 1995 ) 486DX4-100, Low budget Win95 “Plug-N-Play” build.

yeah almost identical. Mine is -S4 (silkscreen on the board) or -S7 (POST BIOS string)

2 questions for you:

1. Does your secondary IDE port work? Mine doesn't.

2. Can you set the CPU voltage to anything but 5V? I can't. Well the motherboard pretends to have a jumper for voltage, but it doesn't do anything. I see that your motherboard doesn't have a voltage regulator installed, and you're using a SK096 which is a 3.45V CPU. Have you checked the actual voltage that the CPU receives, because I'm afraid you're overvolting it.

stamasd wrote on 2022-01-31, 18:09:

kolmio wrote on 2022-01-31, 16:57:

Isn't plugging a 3.45 volt CPU into 5 volted socket a sure way to fry the CPU?

I use a Pentium Overdrive PODP5V83 which has its own on-board voltage regulator. It's made for working at 5V.

Good. You first mentioned using X5-133, that's why I made this notice.

kolmio wrote on 2022-02-01, 10:12:

stamasd wrote on 2022-01-31, 18:09:

kolmio wrote on 2022-01-31, 16:57:

Isn't plugging a 3.45 volt CPU into 5 volted socket a sure way to fry the CPU?

I use a Pentium Overdrive PODP5V83 which has its own on-board voltage regulator. It's made for working at 5V.

Good. You first mentioned using X5-133, that's why I made this notice.

Yes, but I quickly switched it off when it didn't POST. I checked that CPU in another motherboard and it works fine.
Oddly enough, a Cyrix 5x86-100 worked fine in the motherboard at 5V, even though it's a 3.3V chip. After I realized the problem, I didn't fire it up again like this though. 😀

Did voltage mod on the ODPS5V83 with 2 Schottky diodes in series, CPU voltage is now 4V and it is completely stable at 100MHz (40x2.5) in all games and benchmarks I tried.