I knocked off the 270uf 16v input filter cap from my mobo and it works fine - Page 1
Forum section: electronics / beginners

author: clickcell
author_rank: Contributor
timestamp: August 03, 2020, 09:52:11 pm
content: It was a Nichicon aluminium electrolytic, from a board that has run 5 years 7 months continuously.There is only one capacitor of that value, a few 110 16v in other locations on the board.Should I just continue running it without that cap? Would the cap still be in spec after almost 6 years at 50c?What is the purpose of a 270uf cap? I know it is to smooth out the 12v input from the psu, well how much smoothing is 270uf? How much smoothing can that cap do new vs after 6 years of use? If the board works now and is stable need I care about replacing it?

author: amyk
author_rank: Super Contributor
timestamp: August 03, 2020, 09:54:26 pm
content: Have you actually stress-tested the CPU and other components of the system?Less decoupling will not show up immediately as a failure, but may result in more system instability.

author: clickcell
author_rank: Contributor
timestamp: August 03, 2020, 10:25:51 pm
content: I assembled it on the bench and fired up prime 95 for a couple of minutes. But ran into overheating issues with the cpu and temporary heatsink. It would hit the thermal limit and turn off, I'd stick the heatsink next to a large desk fan to cool it down, put it back on the board, try again, it would work fine again.

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 03, 2020, 10:39:38 pm
content: Reduced decoupling may lead to stability issues. Don't run anything you depend on on that system.

author: clickcell
author_rank: Contributor
timestamp: August 03, 2020, 11:13:22 pm
content: Could it also lead to the system being fine forever and a top performer?

author: Circlotron
author_rank: Super Contributor
timestamp: August 03, 2020, 11:14:30 pm
content: That's how manufacturers likely design consumer electronics. Design it properly then start snipping out parts till it stops, then go back one.

author: Mr. Scram
author_rank: Super Contributor
timestamp: August 03, 2020, 11:24:48 pm
content: Quote from: clickcell on August 03, 2020, 11:13:22 pmFine forever it will definitely not be, as is the case with any system. Reduced decoupling is likely to decrease the margin of error, which means aging and wear may become troublesome sooner. The same applies to performance. It's very possible you'll never notice a thing but it does add more uncertainty to the setup.

author: clickcell
author_rank: Contributor
timestamp: August 03, 2020, 11:38:25 pm
content: Was there a lot of life left in the cap I knocked off? Would it have lasted another 5 years?

author: wraper
author_rank: Unknown
timestamp: August 03, 2020, 11:40:48 pm
content: Considering capacitance and application, most likely it's aluminium polymer capacitor, not simply aluminium electrolytic.

author: Vovk_Z
author_rank: Super Contributor
timestamp: August 04, 2020, 08:39:05 am
content: Yes, it has to be solid polymer cap. And It is there for lowering the pulsations/noise etc level both before and after DC/DC. It may work without it but radiating more wide-frequency noise.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 04, 2020, 09:29:54 am
content: 6 years at 50 degC does not mean the part has run out of life. If originally good quality and if not overstressed by too much ripple current (whichyoudon't know, but the designer does), it should be OK for another 6 years if not more. The design life for a motherboard is likely not much beyond 5-6 years but that doesn't mean all parts are end-of-life at that point.Trust me, such low-cost mass produced electronics do not use excess meaningless parts. It's there for a reason. The fact it seems to be working well enough for you despite the removal does not mean it's reliable anymore. You have reduced the margins and it can be very close to failing, you don't know that.

author: FriedMule
author_rank: Frequent Contributor
timestamp: August 10, 2020, 09:55:07 am
content: You may be lucky, many boards are build for overclocking and do therefore have some extra margin for safety, but you may also own a slower PC right now. It may not be visible and maybe you won't notice it, but the CPU may make more recalculations because it lacks some stability.