Thank you for contacting the Intel® Communities.
I would like to provide you with the compatible RAM for your Intel® Core™ i5-6500 Processor.
**DDR4-1866/2133, DDR3L-1333/1600 @ 1.35V
Any RAM modules within those specs, should work with the unit.
Have you tried testing each RAM module in each DIMM slot? To discard either the RAM module or DIMM slot as the issue.
DDR4-2133 modules works
I am glad to hear you got compatible module(s), do not hesitate to contact us back if you encounter with any additional or new inquiries.