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.
The A50 and A70 look quite a bit more substantial with their fans attached. Clearance can be an issue for larger air towers, so I’ve taken some additional measurements that might help folks trying to decide whether either beast will interfere with their system’s memory modules or motherboard heatsinks.
Corsair recommends that the coolers are oriented with the fans blowing air across the heatsink and toward a rear chassis exhaust vent. That puts the A50’s fan above the DIMM slots on most motherboards, while the A70’s fans hang over the DIMM slots on one side and power regulation circuitry (plus its associated heatsinks) on the other. If you mount the fans as high as possible, there’s 1.4″ (37 mm) of clearance between their bottom edges and the base of the CPU slug, leaving plenty of room for standard-height memory modules and taller VRM heatsinks.
The same set of mounting hardware is used to strap the A50 and A70 to any recent AMD or Intel socket. Installation is a tool-free process with AMD sockets, but you’ll need to bust out a screwdriver to secure the H-shaped plate to the base for Intel CPUs. Pairing either cooler with an Intel socket requires a back plate whose installation will probably force you to remove the system’s motherboard. Corsair’s own enclosures offer handy access panels to prevent users from having to pull apart their rigs to install CPU back plates, but that’s hardly a common feature among even enthusiast-oriented cases.
Once you have the H-plate installed and the back plate in place, the A50 and A70 sandwich Intel sockets with the aid of four thumbscrews. If you’re working in an enclosure that doesn’t leave much room for your hands, a Phillips- or flat-head screwdriver can be used to turn the screws.
As one might expect, a tube of thermal compound is included with each cooler. There’s enough for multiple applications using the pea-sized dollop of goop recommended by Corsair, and a couple of extra rubber fan posts are thrown in for good measure. I’d like to see at least one extra thumbscrew added to the box, as well.
By now, you’re no doubt wondering how the A50 and A70 perform. The Benchmarking Sweatshop’s collection of CPU coolers is pretty meager, but I do have a Thermalright Ultra-120 eXtreme with similar dimensions and a single 120-mm fan. To see how the Corsair heatsinks compared, I overclocked a Core i7-920 to 3.26GHz with a CPU voltage of 1.144V. My i7-920 is an engineering sample from the original Nehalem launch, so it runs a little hotespecially when hammered with an eight-way Prime95 load. CPU temperatures were monitored using Real Temp, and I noted the temperature of the hottest core (always core 0, incidentally) after 10 minutes at idle and under load. That was enough time for temperatures to stabilize with all three coolers.
The motherboard’s BIOS was configured to run the CPU fan at full speed for each cooler. In addition, the A50 and A70 were tested with their in-line resistors capping fan speeds 1,600 RPM. All testing was conducted on an open test bench.
Only two degrees separate the coolers at idle, and the gaps barely widen under load. I’m a little surprised that there isn’t more of a difference between the A50 and the A70 here, but it’s nice to see that the slower fan speed doesn’t greatly diminish the performance of either model.
That’s particularly important because both Corsair coolers are much louder when their fans are spinning at the full 2,000 RPM. Noise levels were measured six inches from the top edge of the motherboard, but the difference between fan speeds was easily audible from several feet away. At that distance, it’s very difficult to discern a difference between the A50 and the A70 with their fans set at 1,600 RPM.
To provide some context, I should point out that the Thermalright weighs 0.25 lbs (113 grams) more than the A70 and packs six heatpipes, none of which makes direct contact with the CPU. At about $60 online, the Ultra-120 is pricier than the Corsair coolers, too. The A70 costs $48, while the A50 can be had for only $40.
At those prices, the A50 and A70 look pretty competitive. Buy either through Newegg before the end of the month, and you’ll get a $15 mail-in rebate that sweetens the deal. The rebate check will likely take 6-8 weeks to arrive, if it does at all, but just think of how much you’ll enjoy the anticipation.
Given the $8 difference between the A50 and A70, I’m torn on which I’d actually buy were I putting together a new system today. I suppose that would depend on how aggressively I was going to overclock. The A50 can certainly hold its own, but you really don’t have to pay much more to step up to the A70, which can be made quieter by running only one of the two fans.
Honestly, though, I’m not sure I’d use either in my personal desktop. There’s no doubt a lot to like: the Air Series is easy to install, features an excellent fan bracket, and lets users select one of two fan speeds. However, I’d much rather have a CPU fan with a four-pin header that’s more cooperative with BIOS-level automatic fan speed controls, and part of me can’t shake the suspicion that direct heatpipe contact might not be worth the crevices that line the base of each heatsink.