The board very likely has jumpers on it which dictate the set voltage. On socket 7, it's anywhere from 2.5v to 3.5v. Look up details for your motherboard to see info on how the jumpers should be set for the voltage, or maybe you have a diagram silkscreened somewhere on the board.

brian105 wrote on 2021-01-20, 03:19:

The board very likely has jumpers on it which dictate the set voltage. On socket 7, it's anywhere from 2.5v to 3.5v. Look up details for your motherboard to see info on how the jumpers should be set for the voltage, or maybe you have a diagram silkscreened somewhere on the board.

I’m going to be using undocumented jumper settings which is the reason for this post. I’m aiming for 2v or less. But can settle as high as 2.2

Take a look at socket 7's schematic

I think the pin you want to measure is a VSS pin. There are many around the socket but one that's easy to find is the one near the "key" pin.

Deksor wrote on 2021-01-20, 17:02:

Take a look at socket 7's schematic […]
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Take a look at socket 7's schematic

I think the pin you want to measure is a VSS pin. There are many around the socket but one that's easy to find is the one near the "key" pin.

Perhaps the one opposite of the flat corner is easier to be sure about cause the one by key flips with orientation

Vcc to ground to get reading?

Aren’t there two voltages? One for I/O and one for core? I need to check core yeah? Is that the vcc?

My preferred way is to stick a dual voltage chip that is 'high-voltage' tolerant, like a 6x86MX or first-gen K6 with the board set for a supported/known voltage. After powering on it's quite easy to find a measuring spot, usually it's the tab of one of the mosfets. After that it's safe to play around with jumpers, because a 2.9 or 3.2v chip shouldn't immediately destroy itself at 3.5v (and usually this voltage is among the marked ones so no need to go that high).

A good practice is to search for the datasheet of the PWM chip, in most cases this provides sufficient information (and sometimes closer to the truth than the board's silkscreen or manual).

quicknick wrote on 2021-01-20, 21:36:

My preferred way is to stick a dual voltage chip that is 'high-voltage' tolerant, like a 6x86MX or first-gen K6 with the board set for a supported/known voltage. After powering on it's quite easy to find a measuring spot, usually it's the tab of one of the mosfets. After that it's safe to play around with jumpers, because a 2.9 or 3.2v chip shouldn't immediately destroy itself at 3.5v (and usually this voltage is among the marked ones so no need to go that high).

A good practice is to search for the datasheet of the PWM chip, in most cases this provides sufficient information (and sometimes closer to the truth than the board's silkscreen or manual).

The top tab? The one that sometimes has a hole for screwing to a heatsink?

Sounds like a good method thanks

So if there are two fets one is I/O and other is core?