namely, it is supposed to be, depends on the quallity of the PSU. My opinion is to always get a tier 1 PSU. About Wat go maybe higher than your needs, this is how i buy at least. This way you are 100% sure your system is powered correctly, your parts are safe from anything and you are future proof.
mixing memories is NEVER guaranted to work, only memories from the same package are guaranted to work together.
Also, you didn't talk about the frequency of the RAM , CL etc . RAM is not all about bandwidth(GB).
namely, it is supposed to be, depends on the quallity of the PSU. My opinion is to always get a tier 1 PSU. About Wat go maybe higher than your needs, this is how i buy at least. This way you are 100% sure your system is powered correctly, your parts are safe from anything and you are future proof.