Precision 7740 not starting with new RAM

Hello everybody,
I have DELL Precision 7740 with 32Gb Ram and I would like to add another 32Gb.
I would buy exactly same ram as I have now, but its quite hard accesible in my place and I didn't know that it could be such an issue.

I would be gratefull for any advice according to RAM addition to one that I have now or if would it be easier to replace RAM completly.

According to documentation 4x16Gb is fine for this model.
Currently I have 2x16Gb SK Hynix HMA82GS7CJR8N-VK DDR4-2666 (DataWidth 64)
I bought Kingston FURY 32Gb(2x16Gb) 2666Mhz CL16 Impact (DDR4)

Thanks in advance for any advice