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I was upgrading my laptop's RAM and, after removing a module, one of the little grey things (circled in red in the image below) came off.

enter image description here

Can someone please tell me what this is?

And if it is dangerous, as in, should I replace the module that has this problem?

Thank you.

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That is most likely a capacitor (edited - previously posited it was a resistor or diode).

While not dangerous in the traditional sense, it is necessary for the proper and consistent functionality of the RAM module. So YES you should consider this module busted and replace it. A decoupling capacitor acts as a noise filter that will help clean signals on the module, without it then signal noise could cause bits to flip improperly/unexpectedly. While that won't fry your PC, it could cause "strangeness" in your programs or OS, from hiccups in operation to bad data saves or full system crashes. If the PC isn't in an electrically noisy environment, you may not even notice a difference. That said, I'd still replace as soon as I could.

As a general rule when bits are removed from (or fall off of) an electrical circuit, it fundamentally changes the properties of the circuit making it so that it won't operate as intended (if at all). Which is a polite way of saying "broken".

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  • Can I keep using this module until I get the new one, or should I remove it immediately?
    – m-oliv
    Feb 24 '17 at 21:37
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    If you put it in the computer, and the computer is actually working you could try to keep using it. I would strongly suggest you run a full memtest86 for a couple passes before you trusted it with any actual data. If is broken in a way that makes it seem functional but corrupts your data then you stored data on your drives would become corrupt as you modified them. tl;dr best to just not used it, second best is to only use it after it has passed memory tests.
    – Zoredache
    Feb 24 '17 at 21:52
  • @Zoredache I ran a memtest and it passed, that's why I'm using it. I'll get the new module by wednesday, at worst. However, I'd like to keep using this one until then. But, if it fails memtests, I'll remove it immediately.
    – m-oliv
    Feb 24 '17 at 22:11
  • "That is either a resistor or diode" -- It's far more likely to be a capacitor than a diode. And based on the brown body color, there's 99% chance that it is a capacitor.
    – sawdust
    Feb 24 '17 at 22:40
  • @sawdust does that mean that the module can damage the computer?
    – m-oliv
    Feb 24 '17 at 22:47
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Those are almost definitely capacitors. I know because we use them extensively in electronics.

The design of the board and position of the capacitors makes be strongly believe that they are simply decoupling capacitors, we put them across the power line and ground on a microchip like this as a filter to get rid of any noise on the chip power supply.

It having been knocked off will not damage your computer unless it tore a bit of track so that the pads are now shorted together. Make sure that the pads are clear. Other than that the worst that would happen is the memory module might "misbehave" at times, though it would be difficult to say how problems might manifest.

The capacitor is essentially an open circuit to DC voltages, but effectively connects high frequency noise to ground. There are generally a few placed close together near any lines that need protection, and loosing one probably won't actually affect the memory module much, if at all, but it might.

In case you care, the little black 8 pin packages at the bottom are 4-way resistor packs, almost certainly terminating the data lines going to the chips.

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