Is It Normal for the Capacitors to Get Warm in Operation?

[The_Doctor]

I've just got two new Intel D865PESO motherboards off of eBay, one is to replace a failed board in a friend's P4-3.2Ghz System, the other one is to replace the motherboard on a p4-2.4Ghz system that originally had onboard video. That computer is being used to run a CNC milling machine, and apparently onboard video oftentimes does not work well with the machines real-time functions. Enough about what I'm doing with them, let's get down to the question.

I installed the 3.2 GHz Pentium 4 onto one of the boards, along with one gig of memory. I did not install it in a case, it's just laying out exposed and hooked up to a power supply and monitor, just to make sure the CPU and memory actually still work. Well, it boots into Windows no problem whatsoever and shows absolutely no instability, but I accidentally bumped one of the capacitors up near the CPU voltage regulator, and noticed it is quite warm. I then started feeling several of the capacitors near the CPU, they are all quite warm, actually a bit warmer than the CPUs heatsink. You can hold your bare finger on them, but they are warm enough that it is not comfortable. I also noticed that some of the other capacitors, not located near any components that all these we use a lot of power, are at least moderately warm.

I have never actually checked the temperature of capacitors in a switching power supply, so I don't know for sure, but this does not seem normal to me. I am used to large electrolytics that are simply rectifying 60 Hz AC, and they never seem to get warm at all unless they happen to be located near one of the power tubes. Is it normal for several of the capacitors on a motherboard to get rather warm like I'm seeing, or do I have a motherboard which is basically ready to die right out of the box?


Thank you
Ed

[stevo1210]

Re: Is It Normal for the Capacitors to Get Warm in Operation?

The capacitors that around the CPU tend to get quite warm. So that would be normal and I would not be concerned about it if I were you. If they are getting really hot, I'd be wary as the hotter caps get, the shorter thier life becomes.

[kc8adu]

Re: Is It Normal for the Capacitors to Get Warm in Operation?

much of the heat is conducted to the caps from vrm parts and the cpu itself through the board.

[PCBONEZ]

Re: Is It Normal for the Capacitors to Get Warm in Operation?

As said caps will get warm due to the heat from nearby components.

Also caps dissipate ripple as heat.
A cap that's dealing with excessive ripple will be hotter than one that isn't.

A cap that's failing will also get hot.
As they go bad the current through them goes up and that creates more heat,,
which causes more damage -> more current -> more heat in a cycle until it burns open or shorts.

.