What exact ram model or what voltage specifically is the ram you have? If it's above 1.35V, I advise to keep it away from kaby lake as it can damage the CPU over time. (That applies to Skylake and I assume to kabylake as well).
Chances are you're using DDR, not DDR3L which is what you need. The standard spec for DDR3 was 1.5v, DDR3L is 1.35v and is needed so you don't eventually fry the memory controller on kabylake. So I'd look at budgeting for new RAM.
*edit Rexper also nails it with the chipset issues. I don't belive there is a kabylake chipset that does DDR3L, so you'd need to have access to a skylake CPU to update the firmware of the motherboard. If you don't know someone with a CPU you can borrow you'd have to pay someone to do it for you, which eats up any savings you would have had by sticking with your older RAM. Overall it's just not worth it to try and stick to the old generation of RAM.
Shortly speaking - don't even try that. There has been someone on this forum who has tried to use DDR3 ram with SkyLake CPU. While the machine worked, its performance was *dramatically* low, and he ended up buying new motherboard and DDR4 ram.