1/2' ID which makes a 5/8" OD
I soldered on some fittings with 1/2" pipe threads on em. So now I can put whatever I want, for barbs, on it. In this case I twisted on a couple brass 1/2" hose barbs.
I set the new radiator up quickly and for quick testing/reference. For the moment it has two 120mm fans just resting up against it and held in place with zip ties. They are old crappy fans that are barely good for anything other than just moving a little air, but they spin and are the only 120mm fans that I have at this moment. This setup is with no shroud and the radiator outside of the case.
I'll be building a housing/shroud here soon.
After my system warms up, the temps are as follows with an ambient of 77F.
30c idle (warmest core the other 3 are 1c - 2c cooler.
50c Full load, all cores, Prime95, large FFTs after an hour, the other cores are only 1 degree cooler and fluctuate a bit, up to -3c difference of the warmest core. Edit: I should have continued testing on Prime95 the temps were rising at this point and they probably would have went higher.
This is a substantial drop from the other radiator and is bound to get better once I have better fans and a shroud. I'll post back when more work is done.
I also have an E5200 and I will be testing how well this works with it as well, so I have some dual core results in the mix. I do not plan on testing the E5200 until I have the shroud built.