Can anyone please explain the CV system?

Bundle value is capped if you never give away non bundled titles. It describable this on the page where you make giveaways, and in the FAQ. I recommend you read one of those.

Some games are classified as bundle games, you can see which ones those are either from the bundle list or when creating a giveaway, the game name will have a start (*) right next to it.

If you gift bundle games only your max cv will be 30.

After that, afaik for every 10 $ "real" CV you gift, any left over extra bundle value will be counted as 20 % of it's real value.

For example, you gift 50 $ in bundle games, your Cv will be 30

Then you gift a 20 $ non bundle game
Your CV will then be 30+20 = 50 + 20*0.2 = 54 CV.

If you gift 33 in bundle and then gift 20 in real your CV will be 53.

Games which have been in bundles or otherwise made widely available at little or no cost are added to the bundle list. Games in this list will not add more than 20% (1/5) of your non-bundle contributions, disregarding the first $25. For more detailed information, see this thread.

In order to receive any additional value from your current bundle gifts, partial or otherwise, you will need to contribute more in non-bundle games.

Oh, Thanks to both of you, goodnight :)