OK, a few clarifications need to be made here - the ivy bridge i7-3770k runs considerably cooler than the i5-4670. Haswell is known to run hotter. As proof, look at a recent review of Top end air coolers on the Haswell chip, they perform far worse than on Ivy, and ONLY TOP end are recommended for OC http://www.tomshardware.com/reviews/best-heat-sink-haswell,3554-22.html
- it couldn''t even handle an Ivy bridge clock to 4.6!
Now, if you then compare the 120M to other AIO closed loop coolers, you find it is mediocre at best and performs at the level of a Corsair H60. And the ONLY comparisons you can find are on Ivy chips as it is not recommended, and therefore not tested, on Haswell. http://www.overclock3d.net/reviews/cases_cooling/cooler_master_seidon_120m_review/6
Comparing results, we know that the top end aircoolers in that Haswell review perform better than an H100. If the 120M only performs at the level of an H60, obviously it is a bad choice for overclocking Haswell.
Bottom line, if you want to overclock Haswell, at the very least you need a H110 level cooler - AT LEAST. The top end air coolers listed in that review have all been tested to outperform the H100 and H110. And they are quieter too....