I would guess to use the software that came with the card
Edit: PNY does not provide any RBG software with the card, so you'll need to dwnld it over here https://www.pny.com/promo/consumer/velocityx-verto
GPU Boost is an algorithm the GPU uses to clock up and down based on power draw, temp, voltage, and application. It's automatic between GPU and drivers. The colder the GPU is, it'll clock as high as it can for as long as it can if it has the power budget to do so. With the 3000 and 4000 series cards they are mostly voltage capped rather than temp capped. So trying to increase is rather fruitless unless you can get them real cold.
I suppose the manual overclock is for those who want the maximum at all times.
However I see no need to mess with overclocking as the PC plays fortnite at max graphics settings and I can stream at 720P 60 with no issues whatsoever.
I used velocityx because it has the RGB control for the graphics card.
I use MSI Afterburner on one of my older PCs.
I may look at it for this one, but how would it work with velocityx running for the RGB or is it that the card stores the RGB setting internally and the program doesn't need to run for it to work.