Can size

[uligli]

Greetings, i've always had this doubt about if the size of a cap does matter when is about perfomance. I'm recapping one of my old PSU, Hiper TypeR 580w, and it has a 3300uF 16V cap which is bigger than the new cap, same height but the old cap's diameter has 3 or 4 mm more than the new one, is it ok to use it even is smaller?

Old cap: JEE 3300 uF 16v "Low ESR" printed on the cap
New cap: Samxon 3300 uF 16v RS

[999999999]

Re: Can size

^ Yes and no. Higher quality design and newer tech can make a smaller cap have the same specs, but all else being equal using today's best tech, a physically larger cap will have better specs.

Consider the space available for a larger cap to be an opportunity to use a better cap. For example in the same Samxon family one rated for higher capacitance and voltage, or an overall better capacitor make and model.

So generally speaking, it is seldom the case that it's a good idea to replace with a smaller capacitor because you can upgrade the component instead, except that with solid rather than electrolytic caps in certain switching circuit filtration roles, the goal of lower ESR is reached in a smaller physical size already.

Beyond that it's about specifics... what type of circuit it is, where the cap is in the circuit, and the specs for both the old cap and new one being considered. Size matters but it's more of a reflection of the other parameters rather than a primary consideration, until the cap is too big to fit in the available space or the opposite, the lead spacing is too small to use it without spacing it away from the board or bending leads in awkward angles or drilling new holes to mount it, etc.