No real benefits? If where not talking about temperatures, there are other benefits to AIO watercoolers.
Ram compabillity:
Dosent matter which ram modules you use since the cpu block is not going to interfere with the ram like it does on some big tower coolers
More effecient airflow:
AIO coolers CAN improve airflow since you mount the radiator directly to the case and not in the middle of it. Many cases have limited airflow over the CPU compared to a direct intake.
That being said I have nothing against tower coolers. I just didnt agree that AIO have no benefits . An example is the brilliant noctua d15. Beats many AIOs, but it is also a gigantic tower cooler.
Yup.... absolutely NO BENEFIT..
Space... just get a bigger case
Cooling... Overclock cpus do not benefit from upper bound cooling, because they top out @ 4.8 ghz within 60-90C makes no difference where you land on that...
Cooling... Stock cpus can use stock cooling, you're just blowing money...
Longevity... the AIO coolers are bad and will crap out long before your CPU does...
More efficient?... the biggest aio coolers have only a slightly lower upper bound temperature than the large 120mm towers which cost 1/5th the price..
The reason... DELID....
If you don't Delid your CPU, you're doing something wrong... it is VITAL on all modern haswell and Ivybridge.
If you have a COMPELLING REASON to use a smaller case, "out side of, my girlfriend thinks it looks cute"... then, perhaps yes, AIO is the way to go..
Smaller Case = BAD 99% of the time.. due to cabling, and heat.. even in this scenario, if the Tower FITs, the reliability factor still means you should use a tower.