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0402 Capacitor Values under 12900K IHS


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Hi,

This is a long shot, but does anyone know the capacitor value for the tiny 0402 capacitors on the 12900K under the IHS?

I am also wondering if the function of these capacitors is known. They look small for decoupling to me.

I stupidly knocked them when delidding as a shaving of the silicone I was removing hid them - turns out my eyesight is not what it used to be. I think I have stared at one PCB too many!

Here's a photo of the capacitors. I have surface mount tools, so should be able to get them back on, but I only have one of the two. I did have both, but a little too much tension in my tweezers and the little critter launched itself like a flea, never to be seen again.

If anyone knows the value or function then great. If not, I'll try to measure the remaining one with a capacitance meter and post back here.

Thank you @der8auer for your excellent delid video, so I can get the orientation right when I put them back... hopefully! Your comment of 'Good luck putting those back on if you knock them off' has made me kick myself several times, especially since I watched your video twice before attempting the delid myself! 🙄

Steve

12900k Delid.PNG

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So, based on my measurements, I reckon these capacitors are 33pF (Pico Farads).

I measured the capacitance of the one that remained (the one I didn't lose!) using a cheap LCR meter that I got from Amazon. I had to calibrate this meter+leads off some known capacitors I had hanging about.

I will order some replacements and see how it goes.

Here's a photo of the capacitor I knocked off next to a standard ceramic capacitor of the same value, to give an idea of size - I have never handled SMT components this small before. Incredible!

I haven't pinned out the CPU to work out what they are connected to. I would do this, but I would need to solder onto the pad, which risks damaging the tiny area before soldering replacement capacitors back on. As there's a pair and they are very small values, I don't think they will be decoupling, I reckon they will relate to a differential bus of some sort - part of a PCIe lane perhaps, I don't know. I think I should put them back!

Steve

WIN_20220219_21_46_29_Pro.jpg

WIN_20220219_21_44_58_Pro.jpg

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