Photos and Fitment
So before we get into testing these two heatsinks I did want to take a look at them individually. With that, I also want to talk about how they fit on our Gigabyte AB350N Gaming WIFI. It has a very unique layout for a Ryzen ITX board that helps with heatsink clearance but hurts with plug placement for all of the power connections.
Anyhow so here is the NH-L9a-AM4, unlike the NH-L9a this is actually a different heatsink from what Noctua made for their original AMD cooler. The other AMD design used the same square heatsink that the Intel focused L9i used. Here you can see that the heatsink is rectangle shaped to better take advantage of the extra space that AMD allows them to have. Sadly though that same wide design isn’t really possible to match with the fan so the extra heatsink just sticks out the ends past the Noctua NF-A9x14 PWM fan. I’m excited to see if it helps cooling performance at all, but given the longevity that the AM4 platform is planned to have I’m glad they made a cooler specifically for it. The Noctua NF-A9x14 PWM fan is the same fan on all of the NH-L9 models, they use this one because it is thin and has a wide RPM range to help push air when needed.
The whole point of this cooler though is to stay low profile in the CPU socket footprint. This means the NH-L9a-AM4 actually fits even with a low profile memory kit and actually uses all of the space that is normally empty or heatpipes on a larger cooler. They have an aluminum fin design with Noctua logos on both ends. One end also has two heatpipes visible.
The key to being this low profile is all in the mounting design and this is why these use a different mounting setup than all of the other Noctua heatsinks. The brackets that attach to the heatsink mount right to the motherboard and there obviously isn’t room to get to the bolt so they are installed from the back of the motherboard. Unlike a few heatsinks with this design, Noctua does use a thick backplate to prevent damage to the board and to help keep the clamping pressure from bending the socket.
Now there are only two mounting options and they don’t really make any difference other than which way the fan cable faces. Add that to the design sticking entirely inside of the socket and in line with the rear I/O and near the height of the memory there aren’t any concerns with fitment. This is going to fit in any case and on any board with any memory. The only concern is if it will have enough cooling power to get the job done.
I got a few shots of the NH-L9a-AM4 next to the NH-L12S and you can really see the size difference between the two coolers. Both on height and the overall size. This is also a great example of how much room the mounting setup takes up on even the best heatsink designs.
So with the NH-L12S out you can see that it uses a horizontal design with a single or dual fan mounting configuration. For our testing today I am only using the single bottom mounted NF-A12x15 PWM because this is how the L12S ships and how most SFF systems would use it. The cooling surface is not only larger because of the 120mm squared size but the thickness is also a little thicker so there should be a performance difference between this and the L9a-AM4. This design floats by the heatpipes and they do tend to get bent down a little as you can see, you can pull it back up once mounted if it is a concern. The NF-A12x15 PWM is one of Noctua’s newer slim fans where the original NH-L12 design used a thicker fan on the bottom, not to mention it was a smaller size (92mm vs 120mm). So the older design basically needed to have the top mounted 120mm fan for cooling where this design can just use a second fan for a little extra help or if you want you can mount the included NF-A12x15 PWM on the top, not the bottom.
Noctua went with 4 heatpipes to pull all of the heat up from the mounting surface and across the heatsinks.
Then for mounting it uses the traditional Noctua mounting system. I’ve seen them change this a few times over the years but not for a very long time. Yet almost no one can come close to how easy Noctuas are to install. That doesn’t even include how nice it is that they always bring out mounting brackets for every new design and provide them for free when needed. Typically you could run an old Noctua cooler and just upgrade the brackets to a new design.
Now their surface finish has the same slightly polished but still rough finish that they almost always have. I’ve never understood why they don’t go for a complete mirror finish, but typically the performance numbers have been good so I can’t complain too much.
So unlike the L9a-AM4 the L12S actually has a few mounting options that could change the way things fit. I did a test fitting of each of the four configurations so lets quickly run through them. It all comes down to if you are using the long brackets or the short brackets really. From there you can flip one way or the other. When using the long brackets the widest part of the heatsink will go from the top of the motherboard to the bottom. So clearance for the PCIe slot is a concern as is anything up on top. For this specific board that means that getting to the 24-pin and SATA connections could be tight.
Clearance in both long bracket configurations put the fan over the first stick of memory. Our short sticks fit but if you had tall memory it wouldn’t work.
Here are the long brackets with the heatpipes on the PCIe side. You can see the video card has better clearance but the top of the board has less.
So then a swapped to the short brackets that mount at the top and bottom of the board. You can also see I almost forgot to take the picture and had already put the heatsink down on it with thermal paste, oops!
So with the short brackets, you can pick from having the heatpipes over the memory or over the rear I/O. With them, over the memory, there is a touch more clearance though I wouldn’t call it a lot. I think you might be able to get a taller memory stick in there but not some of the tallest memory kits. In that configuration, some of the cooling blows down on the rear I/O. Flipping it around puts the heatsink over your memory but at least that cooling is also blowing down on the memory to keep things cooler. That last configuration is how I tested the NH-L12S.