Asus' Sabertooth P67 is a very good motherboard. We said as much in our review, but there is one catch. The much-touted Thermal Armor designed to better cool surface-mounted components can actually do more harm than good. This plastic cooling shroud largely relies on airflow generated by down-blowing CPU coolers like the ones found with retail-boxed Intel CPUs. The thing is, anyone inclined to spend $220 on the Sabertooth is probably running a tower-style aftermarket cooler whose airflow is of little help to Asus' first attempt at motherboard ducting.
In fact, even using a CPU cooler that channels air toward the motherboard is fraught with peril. When a system is under load, any airflow generated by such a configuration is going to be rather warm, having just passed over the CPU heatsink. You wouldn't try to cool yourself off with a hair dryer, now, would you?
Fortunately, all is not lost. The Sabertooth has a built-in mount for a 50-mm "assistant fan" that can be used to generate airflow for the armor. Asus doesn't actually ship a fan with the board, though. Five-year warranty coverage is a defining feature of the Sabertooth line, and qualifying a fan for that lifespan would have been too expensive. Instead, Asus thinks you should supply one of your own.
The company was, however, kind enough to send us a 50-mm spinner for the Sabertooth. Yes, being a member of the tech press has its perks. Free fans!
Naturally, we had to see whether Thermal Armor might fare better with its intended sidekick in place. We populated the Sabertooth with a Core i5-2500K and tower-style cooler, added a Radeon HD 5870 graphics card, and filled out the rest of the system inside a Cooler Master Cosmos enclosure. The Sabertooth has pretty decent BIOS-level fan speed controls for the system, CPU, and assistant fans, so we let all of them be governed by the default temperature-controlled Q-Fan setting.
The first thing we noticed when installing the fan is that it restricts the length of expansion cards that can be used in the top PCI Express x1 slot. Even at only 10 mm thick, the fan sits tall enough to create problems for cards that extend more than about an inch from the back of the x1 slot.
We tested the system with a combined load of Prime95 and the rthdribl HDR lighting demo and used Asus' Thermal Radar application to monitor component temperatures. Testing was conducted with the Thermal Armor on its own, with the assistant fan, and once more with both elements stripped and the board completely naked. The fan was tested blowing down toward the motherboard and sucking air up from inside the armor.
Clearly, the assistant fan makes a difference. Component temperatures under the Thermal Armor were as much as 13°C cooler with the fan in place. Surface-mounted components ran cooler with the fan serving as an intake for the armor rather than as an exhaust, and it's interesting to note that the former configuration resulted in slightly lower CPU temperatures. The assistant fan ends up right next to the CPU cooler, so it's probably has a hand in channeling hot air away from the heatsink.
We should also note that the presence of the assistant fan allows Thermal Armor to produce lower component temperatures than with the board stripped bare. That bodes well for Thermal Armor as a concept, but there is one fly in the ointment. The assistant fan peaks at well over 5,600 RPM with this particular configuration, and you can definitely hear it. There's a distinct, turbine-like whir that reminds me of the noise generated by older graphics coolers.
Asus does provide ample fan controls in the BIOS and through its Thermal Radar software, so you can easily tune the fan's behavior to fit your needs. I suspect you'll be able to find fans that run quieter than the unit we used for testing, as well. However, the fact remains that smaller fans tend to run louder than larger units because they have to spin at higher speeds to generate a decent amount of airflow.
In the end, my impression of Thermal Armor remains largely the same. Because the shroud is likely to result in higher component temperatures without an assistant fan, a fan should absolutely be included with each and every board. I'd rather have the Sabertooth without the armor, though. The naked board should run cool enough in a well-ventilated case, and I'd prefer to trust my system's airflow to larger, quieter fans.