Which RAM modules have you people used in your NUC7CJYH?
Intel's recommendations typically do not list many models of RAM that are available widely, for example on Amazon or Newegg.
Kingston HyperX HX421S13IBK2/8 works fine, but is 2133MHz module.
Kingston HyperX HX424S14IBK2/8 works only when one module is installed. Two modules does not work even if they're a kit and work fine in other computers.
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Intel® NUC products are tested with a variety of memory modules to ensure system functionality. I advise you to review the recommended system memory for the Intel® NUC Kit NUC7CJYH https://www.intel.com/content/www/us/en/support/articles/000026574/mini-pcs/intel-nuc-kits.html here and choose the memory based on the applications and operating system you will be running.
Keep in mind that not every available memory module has been tested and manufacturers usually make changes to their products that may affect performance.
I was recommended at a store to use Patriot PSD44G240082S. I can confirm that this Patriot memory does not work. I wasn't sure where to post this information and found this thread. I replaced with Crucial CT4G4SFS824A and NUC7CJYH booted fine.