Advice wanted for GPU's using Plex in HTPCs



Hi I have my 2 HTPCs GPU specs below.
They are Shuttles, one is XH81v and 2nd is...

Integrated Intel HD graphics supports 4K
(Depending on processor) WHICH IS i5-3470s
Video outputs: HDMI 1.4 & DisplayPort 1.2

2nd is XH61v
Integrated Intel HD graphics
(features depends on processor) WHICH IS i3-4130T
Video-outputs: HDMI and DVI-I

I use HDMI for both btw, now what I wanted to know are these GPU's specs decent or Should I/ Could I improve upon them? Is it even worth it? It's not that I am not happy with anything but really the Volume seems really low on the 61v but I noticed everyone usually gives the advice to have a good GPU for streaming and I was just curious how these stock ones stack up? Thanks for any info