Most Pentium boards provide a way so set the CPU Vcc to the 3.45 - 3.6V range (VRE) instead of the standard (3.3 - 3.45V). I don't think any of those use a separate regulator for the chipset (unless maybe newer boards with dual regulators for MMX support), so feeding 3.5V to the chipset shouldn't be so bad. I assume the 3.3V pins in the chipset are just used to drive the CPU/cache signals? The rest should be 5V.

In any case, if you want to use an adjustable regulator you will need to add resistors in order to setup the voltage divider (there should be an example in the datasheet of the adjustable regulator you want to use). But unless the board has provision for this, you'll have to bodge something.

Yeah I understand that, just wanted to know if 3.5V is too much?

I have knowledge to do the bodges and I have DC-DC converters somewhere to use to bodge onto this SBC.

On this SBC, no provisions to adjust or add components, just fixed.

Cheers,

Hmm according to the Datasheet the output should be +/- 2% so 3.5 is OOS for fixed 3.3v. https://media.digikey.com/pdf/Data%20Sheets/S … 83_12-21-05.pdf
I think using a variable would be a good idea, or find another fixed 3.3v that closer to spec....

The intel 430HX chipset operates with 5V supply voltage. Some I/O interfaces operate at 3V, some at 3/5V and some at 5V.

The onboard voltage regulator on non-split voltage socket 7 mainboards provides a voltage that depends on the CPU core voltage needs (3.3, 3.45...).
A voltage of 3.5V that results in 3.5V I/O signals (for example CPU or PB-SRAM) will not overheat the northbridge/chipset.

If it's outputting ~3.5v it should be the adjustable voltage regulator(the lower one in the schematic, 3.45v out) and you should be able to change the output voltage by changing the values of R1 and R2 using the formula.

Thank you, like I said the regulator used on this board is fixed to 3.3V and no provisions for external components' nor any pads, I have to replace the linear regulator with the adjustable VRM either homemade module or use of these switching DC DC modules.

The fixed EZ1083CT-3.3 "adjust" pin is grounded. 5V supplies the regulator and outputs regulated voltage.

Cheers,

Then, i agree, try with lower voltage, usually 'undervolting' makes things run a little more cooler, and even if Intel states 3.2v-3.45v, it may run happy at just 3v because silicon dies are not identical (that's why you have a range of voltages). If you don't have extra pads, you can get the adjustable version and use the 'legs' of the voltage regulator to ad the extra two resistors.

As mentioned above by majestyk and myself, the HX chipset works on a 5V supply. The 3.3V is used for CPU/cache signals so it won't make a difference when it comes to the temperature. Also, 3.5V is within the expected range for certain Pentium CPUs (VRE, 3.45 to 3.6V), so the chipset should be able to handle 3.5V on those pins without any issues.

How hot is the chipset? It should normally run quite warm, but if you suspect problems (i.e. it is so hot that you can't keep your finger on it) I would check the 5V line instead.

I understand that we are talking about i/o voltages, but if you make an analogy with 'newer chips' and 'modern OC' playing with i/o voltages can reduce temperature also. He has nothing to lose, and i think he understands. At worst he will pay for a extra regulator and two resistors. Also checking the 5v line will not hurt.

I have two different SBCs, both are 430HX, one is cooler, and this other one is hot and this actually browned the chipset's plastic package.

I thought the 430HX core runs at 3.3V and some for 5V to be compatible with 5V interface. Right now datasheet is poorly documented. I need different documentation to study the information.

Cheers,