Say what? The NH-d15 is a heatsink that comes with two Noctua fans. Some of us want to run 100 cfm Sanyo Denkis or what have you on heatsinks like that. Who said anything about a PSU?
The Ultra120 was/is also a heatsink, not a PSU . . .
I don't know if this review is the only place the issue has been noticed, but it looks like they've gone from blocking RAM slots to the first PCI-e slot. Hmm. That could be a problem for some.
It definitely outperforms the D14, at least when comparing the stock fans for each.
I can say something about that -- the size maybe interfering with a gfx-card slot. I'd rather doubt this is going to happen on various mainstream ATX motherboards, especially with a Noctua product. But if it does, it may not be sufficient reason to choose some other cooler -- if the D15 fills your bill and floats your boat.
It is very easy to turn the double-tower at a right-angle to the usual orientation if doing so eliminates any such interference, and you can still get the same CFM throughput and exhaust to the case rear with some very simple modifications. By this, I mean limited ducting to obstruct airflow between the towers and assure that all air sent to the exhaust fan goes through the cooler fins. If done properly, this might even enhance airflow through the cooler as opposed to the usual orientation. At one time, I even proved slightly better cooling on a single-tower TRUE cooler sucking air through its narrow end.
In the end, it's all about trade-offs between desirable results and your priorities. For instance, given the RAM options I've had, I'd rather forego the "tall" RAM modules with enormous heatsinks. My red G.SKILL GBRL's fit fine -- it's a little tight, but I don't need to remove the cooler to remove any RAM module.
On the matter of "100 CFM" fan choices -- you got that right!! I'm repeating myself again: Every so often I run IBT or LinX under my current fan-profile so I can "pinch" myself at how quiet my Gentle Typhoon AP-30 spins to within 300 RPM of its 4,250 top-end, and still seems relatively quiet except for the air-turbulence -- which also seems like almost nothing . . . At that speed, we're not just talking about your 100 CFM, but more like 120 to 130 CFM.
If you want a quiet fan for 100 CFM, you can pick an Akasa Viper. If you want an "almost" quiet fan for 120, well . . . I posted my photos and explanation with the circles and arrows. In the future, I'll be looking again at the AP-30 for certain types of applications, and the experience under my belt for making them work to my desires.
I'm beginning to wonder -- with that sort of airflow -- if it actually reduces kruft build-up by blowing out all the kruft!