There are two kinds of overclockers in the enthusiast world. One will go to great lengthsand expenseto have the fastest CPU on the block and, more importantly, in the forums. In their pursuit of more MHz, this sect of serious overclockers employs everything from liquid nitrogen to elaborate plumbing for considerably less volatile liquid coolants. The end result isn't always quiet, and it'll rarely squeeze into a mid-tower case, which is why hardcore cooling rigs are mostly restricted to the fringes of the community.
Aftermarket air cooling is much more practical solution, and the one thing that most enthusiast desktops have in common. In fact, replacing a stock CPU heatsink is probably one of the first upgrades undertaken by budding do-it-yourself types. It's easy to see why this gateway drug has such appeal. Cooler swaps are simple enough to be attempted by newbies, and they'll only cost you $30-60. That's small change for an upgrade that can offer a huge step up in cooling performance over the increasingly stunted stock heatsinks included with modern CPUs.
The market for CPU coolers is a busy one, and Corsair recently threw its hat into the ring with the Air Series A50 and A70. Selling hunks of machined metal might seem like an odd direction for a company whose roots lie in high-performance memory modules, but Corsair has slowly been expanding its business to include all manner of enthusiast-oriented products, including PSUs, SSDs, enclosures, and all-in-one water coolers. I've been going back and forth between the A50 and the A70 here in the Benchmarking Sweatshop for the past couple of weeks, and there's quite a lot to like about Corsair's first foray into the world or air-cooled CPU heatsinks.
Corsair sticks with the tried-and-true tower formula for both members of the Air Series line. Heatpipes extend upward and into massive radiators that stack 45 horizontal cooling fins. Each of these skyscrapers of precision-cut metal measures 6.25" (159 mm) tall, which is going to be a tight squeeze in low-profile enclosures but shouldn't be a problem for the majority of mid-towers.
As you can see, the A70 is the wider of the two; its cooling fins measure 2.8" x 4.7" (70 x 120 mm), while the A50's are 2" x 4.7" (52 x 120 mm). This disparity gives the A70 roughly 35% more surface area right off the bat, and that's before you take into account the dimpling that permeates its fins.
While A50's fins are perfectly smooth, the A70's are more pockmarked than a pimply teenager. In addition to adding a little visual flair, dimpling can offer aerodynamic benefits, which is why it's used on golf balls and high-end bicycle wheels. Here, the dimples also increase the surface area of the cooling fins, giving the A70 another leg up on its fraternal twin.
Anyone with battle scars from a PC build will be pleased to hear that the edges of the cooling fins are nice and blunt. I've sliced my fingers while working with some aftermarket coolers, notably Scythe's Ninja, which is pretty much a stack of sharpened shurikens. After several installations of both the A50 and A70, my hands don't bear so much as a scratch. You can handle these puppies with impunity.
In addition to larger fins, the A70 also has one more copper heatpipe than the A50. Each of the pipes measures 8 mm in diameter, and all of them make direct contact with a CPU's heat spreader.
Corsair says this direct-contact approach allows heat to be quickly conducted toward the radiator rather than being absorbed by the base of the heatsink. The bottom of each pipe has been shaved slightly to ensure a flat mounting surface, but the slug that anchors the pipes isn't a perfect fit. Tiny valleys run the length of each heatpipe where it meets the cooler's base. Although these cracks fill with thermal compound, I can't help but wonder if more efficient thermal transfer might be possible with a larger base that encircled each heatpipe tightly.
In its reviewer's guide for the A70, Corsair asserts that using a solid metal base would add "significant" mass to the cooler. To the company's credit, the A50 and A70 are relatively light for their size. The A50 registers 1.5 lbs (677 grams) on our scale, while the A70 weighs in at 2.1 lbs (967 grams). I'm dubious that wrapping the CPU slug around each pipe would add substantially to either total, though.
The same 120-mm fans are used with both coolers. Each has seven blades and spins at 2,000 RPM. With each fan, Corsair includes a small extension cable featuring an in-line resistor that knocks the RPMs down to 1,600. The fan leads are a little on the short side, measuring 8.5" (215 mm) without the extender, which adds 3" (77 mm) of length. There are two fans on the A70, and the Y-cable that consolidates them increases the reach by another three inches.
Curiously, the fans and extenders all use three-pin headers rather than newer four-pin ones that include a control line for more robust speed control. As a result, the fans can't play along with the automatic, temperature-based speed controls built into some motherboards. Despite the fact that four-pin fans have been around since the days of the Pentium 4, numerous CPU coolers stick with the old three-pin design.
Each fan is suspended on a plastic shroud by four rubber posts that should do an effective job of isolating the cooler from any fan-induced vibration. Rubber bumpers are affixed at each corner inside the shroud to further dampen vibrations where the plastic bracket butts up against the cooling fins.
I've used all kinds of funky mechanisms for attaching CPU fans, and the brackets for the Air Series are by far my favorite. They easily snap onto the cooler, and plastic tabs click into notches in the radiator to lock things in place. Removing the brackets is easy as long as you have access to the tabs on one side.
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