So, what makes of aftermarket cards are out there ?
I know of Sapphire. Others ?
Also, what memory they're using ?
I myself has switched from Ref 56 to ASUS Strix Vega 56. The one I had comes with Hynix memory, it could push to 950 mem clock, but it's all invalid shares from there on, so I have to downclock the memory to 890 ish, doing about 1750 to 1800 h/s at best.
How does the noise of the card compare to the ref card? I assume a lot less noise to maintain similar temperature?
Yes, the pros are definitely lower fan speed and noise, you can achieve similar temperature with much lower fan speed, so it's doing 2.2k - 2.5k RPM at the moment.
This is probably not relevant if you are building an open air mining rig, but for my case it's my gaming PC, so another difference is the hot air is not disposed at the rear of the card (Reference), but being pushed within the closed case environment, so you will need a few casing fan to pull the hot air out as well.