Nope, the tube is way smaller (.125" difference) than the barb, wont be able to fit it on.
Generally, you want the barb and tube to be of the same size.
Only exception is 1/2" barbs and 7/16" tubing, that will work since the size difference is tiny (only .0615"). Its actually fairly common for loops to have 1/2" barbs and 7/16" tubing, leads to a very tight connection.
That is called the thread.
Unless otherwise specified, you can assume parts use a G1/4 thread, which is pretty much the universal thread used in water-cooling equipment. Only thread other than that is G3/8, but I have only seen that used on adapters from G1/4. But it is worth making sure that all your components use G1/4.
HAF-X actually, my build log is in my sig if you want to see it.
I actually don't like those clamps now that iv used them, they are ridiculously tight and hard to open, had to use some pliers to hold them open to put them on the barb. Suspect I may have slighty miscalculated the OD of the tubing once you shove them on barbs that are too big
so then the OD of my tubes is how big? this measure system is still confusing me(even though i read teh sticky multiple times) so the ID is the diameter inside so i am going to be using a 3/8" ID and X OD? My biggest fear is that it will leak and destroy EVERYTHING so maybe i should go a tad smaller
The OD is the Outer Diameter of the tubing, so how wide the whole tube is.
On the Primochill tubing we were talking about above, the OD 5/8".
The barbs I recommended are 3/4" OD, so slight bigger than 5/8". But considering that you will be putting the tubing on barbs slight too big, the OD is going to become a bit bigger because of it. You could use 5/8" OD clamps, but expect it to be a bit of an effort to get them around the barb.