Thermalright Gets Back on Top with the Ultra-120

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The Ultra-120 consists of a massive stack of aluminum fins held together by four U-shaped heatpipes. The bottom of the "U" in each heatpipe is permanently clamped/embedded in the base, and eight vertical heatpipe lengths run up through the fins in two groups. There's also a "seam" running down each side. In concept, it's not different from most other tower heatsink except for the odd "bent winglets" which supposedly decrease air restriction. It is possible that the winglets are designed to help the air enter between the fins. If you look at the direction that the fan spins and its relation to the winglets, the winglets may help "catch" the air better. This is conjecture.

No fan is included, as usual for Thermalright heatsinks, but there is no question that it is intended for use with a 120mm fan. Two fan clips are included, as well as a pair of thin silicone strips that are meant to provide a vibration-damping cushion between the fins and the fan.

Quite possibly the tallest heatsink we've ever reviewed.

The fins are tightly spaced in comparison to many of the tower heatsinks we've seen, which suggests it will perform best with a higher pressure fan — unfortunate from a noise perspective, but quite likely to make performance-seekers happy. The fins are slightly contoured so that there is a slight space (3~4 mm) between the fins and the blades of the fan. This is not an uncommon design; the intent is to reduce back pressure from the heatsink, allowing a lower pressure fan to be used. Even so, the space is unlikely to fully compensate for the close fin spacing.

Lots of clearance around the base.

The fins do not start until about an inch and a half above the base, which leaves plenty of room for tall capacitors and heatsinks on the motherboard. Unfortunately, this means that the fan — and the airflow that goes with it — is likely to blow over these components, not through them.

High powered processors generate a lot of heat, and not all of it is generated in the CPU itself. The voltage regulation modules (VRMs) that surround the CPU socket also get quite warm under load, and the Ultra-120 does not provide cooling for them. This failing is common to most tower designs, and it's worth thinking about providing some secondary cooling around the base in a high power system.

Bent fin tips — for what purpose?

The "bent winglets" are probably the most unusual part of the design. The product page suggests that they are intended to minimize airflow resistance, but this seems odd given that they serve to add kinks in the airflow path. As mentioned before, perhaps they are designed to take advantage of the angle of the airflow produced by the axial fans commonly used for CPU heatsinks. Effective or not, the exact technical details are really only relevant to engineers. We'll be happy so long as the heatsink as a whole performs well.

The heatpipes are quite thick, and are nickel-plated, keeping a consistent silvery appearance that looks more finished than it would without. The eight vertical pipes are clustered in two groups of four, with each cluster located about a centimeter from the outer edge of the heatsink.

Heatpipes run up into the body of the heatsink.


Installation is a simple matter, as the Ultra-120 uses a similar mounting system as the HR-01. In fact, mounting clips for the two heatsinks should be compatible with each other, although they come with different clips. The HR-01 included clips that attached to the stock retention module on Socket 754/939/940 systems, and a separate clip was available for Socket 478. This is not the case for the Ultra-120, which uses clips that are secured by metal backplates. It also includes a clip for Socket 775, which was not included with our original sample of the HR-01.

All of the clips work in a similar way. Each clip has a raised bump that fits into a depression in the base of the heatsink. The clip fits easily between the heatpipes, and holds the heatsink securely once it is in place.

One drawback: AMD-based systems, which do not have symmetrical mounting holes, allow the heatsink to be mounted on only one orientation. Until Thermalright releases an S-clip for the Ultra-120, some motherboards may be stuck with the heatsink hanging vertically when it would be better suited to be horizontal, or vice versa.

With the clip in place, finishing the installation is as simple as screwing in the spring-loaded screws until they stop turning. The springs ensure that the motherboard is kept under the correct tension (note that the clips designed for the HR-01 don't do this, and may provide less tension than the stock clips).

The clip fits between the heatpipes into a depression on the base.

The base looks smooth, but is marked with hundreds of tiny ridges that could barely been seen.
They could be felt with a fingernail.

Because no fan is included with the Ultra-120, installing the fan is an extra step on its own. It's a three step process:

  1. Stick the silicone strips on to the fan.
  2. Attach the fan clips to the heatsink.
  3. Put the fan in place and secure using the fan clips.

The only nontrivial step is step two, which is made difficult by unclear instructions and poor fit. The fan clips are made of steel wire that is slightly more than a millimeter thick. Given that the fin spacing is roughly the same, it seems obvious that the clips should be hooked between the fins. The question is where. The photograph below shows the correct position for the fan clip. Hooking the clip around the far end of the metal "seam" is easier and seems more intuitive, but results in a clip that is too short to secure the fan safely. Thermalright's instruction sheet has a good illustration showing "the designated hole" for the fan clip.

Slipping the fan clip into the correct position is tricky because the wire gauge of the fan clip is very close to the size of the hole it is supposed to fit into, and it will not fit unless it is at the correct angle. It took us a minute or two of fiddling before we got it right.

The end of the fan clip needs to slip into the hole in the center of the heatsink —
not around the far end of the metal "seam".

Unfortunately, the fan clips are not compatible with fans with closed screw mounting holes, such as our reference Nexus 120mm fan. We had to cut out the closed screw "sleeves" with a hacksaw before the clip could be slipped into place.

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