Yep, i remember the hype about how well they would supposedly clock on air. Tbh ive not seen that many hitting 5ghz for 24/7 use on reasonable voltage. Even on custom watercooling you will still be temp limited as water makes virtually zero difference over good air cooling on hw.
I second this quote. I tested a 4670k, 4770k, 4690k and 4790k with a Corsair H100i, Noctua D14 and XSPC Raystorm with D5 and 600mm of rad.
The Corsair H100i had the highest temps, but the Noctua D14 and custom loop only had a few degrees between them.
I did found that the DC CPU's did have better temps than the original HW CPU's.
However, the custom loop did improve over the D14 with the 4770k and 4790k when delidded.