Scottmm wrote on 2024-04-26, 16:02:
When recapping a motherboard I know you have to match the capacitance for the caps but can go Higher on the voltage
You can also go lower in the voltage... but you really would have to know what you are doing / where you are doing that substitute.
For example, if a cap filters a 3.3V rail on the motherboard and a 10V cap is fitted in that spot, you can actually drop the voltage rating of the cap to 6.3V, if that is needed to make the cap fit. Likewise, on the CPU V_core, where voltages are often under 2V (at least for anything Pentium 3 and later) you can surely use 2.5V or 4V caps, even if the old caps were 6.3V or 10V -rated. But again, you just have to know what rails go where on the motherboard to make this kind of substitution.
As for using a higher voltage cap than what was originally there - no problem in doing that whatsoever... so long as you can get the replacement cap to fit. Higher voltage caps are typically larger. An added benefit of that, however, is that larger caps have (usually) larger ripple current handling rating... meaning, the cap can take more heating (both externally from the circuit and from its internal charging/discharing in the circuit), which means it will likely run cooler and probably last longer too.
So in general, physically bigger caps = them running cooler. Of course, large space isn't always a given.
Also, the brand and series of caps matters a lot too, as that dictates what impedance and ripple current specs the cap will have.
On that note, you can have a larger general purpose cap still have inferior specs to a smaller cap low impedance / high RC cap.
Moreso to the point, you should look up the datasheet for each brand and model (series) of the old caps to see if the new caps are even suitable in terms of matching or exceeding the impedance and RC specs. The new cap should have same or lower impedance (ESR) ratings and same or higher ripple current (RC) ratings.