48GB RAM as 2 matching pairs?

[danpik]

I'm thinking of upgrading the RAM on a prebuilt machine (I'm running some CAD software that is very RAM hungry). It came with 16GB (as 2 sticks of 8), and I was thinking of either
another pair of the same to take it to a total of 32GB,
or
keep the 2*8 and add 2*16, to give a total of 48GB

For the price difference, this seems better value. Either way, I'd go for the same exact speed and brand (Corsair Vengeance DDR4 3000Mhz) as what's already in there.

Searching around I get mixed ideas on what sort of mixing is okay.
Some say as long as each pair matches and all the speeds are the same it's all good.
What do you think?

(This is for this Ryzen 5800X machine - https://www.pcspecialist.co.uk/computers-for-next-day-delivery/1232/)

 

[loso64]

it is not really adviced to combine rams, even if you were to buy the exact same brand and all, it is not advice to combine it.
If possible and your budget allows it, invest into a proper ram kit, either 32 kit or 64 kit.

the reason you dont wanna combine rams is, that it may cause lot of instability and crashing issues, even between same brand. The ram kits are made from the same bin and fully tested to work together.