Hi lorena, Can you plz list the specific AMD A series apu that you have? I ask because the A8 comes with a built-in, on-board HD 6550D, That's why it's considered a APU and not a CPU. APU means GPU & CPU built into one chip.
Seems as if the HD 6550D destroys the gt 610, Question is how well does linux support the, radeon HD 6550D
http://gpuboss.com/gpus/Radeon-HD-6550D-IGP-vs-GeForce-GT-610
Hmm. Well I have been doing this along time and I can only give advise as to what I would do.
If it is the case that your apu is stronger then your gpu and the apu is supported in linux. I would not install the gpu I would try to take it back and get my money back for it.
I have found over the years that no video card from invidia is worth it's salt unless it comes with a ~120$ price tag. The GTX 750 ti seems to be the one hitting that mark now. My girl has one and it performs well with mint.
But, And a big but here. I personally would not pair a AMD APU with a true graphics card. For gaming (especially the games wine runs best) I would seek out a CPU with no more then 4 core's and good single core performance.
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As far as updates go I'm with booman on mint 17.3 my gaming desktop. I install every mint update thrown at me. I even upgraded from 17.2 to 17.3 no problems.
But this got me into trouble, I had such a great experience with mint updates and upgrades, that when lubuntu 16.04 came out I upgraded a web server to it from 15.10.... And broke every thing.
Moral of the story don't let mint with it's amazing update/upgrade experience let you get complacent on the dangers of it.