Intel Sandy Bridge Extreme Core i7 3960X Reviewccokeman - November 14, 2011
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Intel has chosen to not sell the Intel Core i7 Sandy Bridge Extreme processors with an included heat sink. Sounds like a pretty significant break from the past, where the included heat sink was your key to a warranty if the processor should fail. Knowing that the enthusiasts and most likely everyone who purchases a processor in this price range is going to move up to a higher end cooling solution, be it air or liquid-based, the reasoning makes sense. Intel has jumped into the fray with its Intel RTS2011LC as an option. Intel has chosen to sell this processor with an optional all-in-one liquid cooling solution much like AMD did with the FX series, or if you really want it, a standard Intel-boxed heat sink can be had for around $20. The liquid cooling provider is Asetek, long known for OEM-style cooling solutions. Where this solution differs from the AMD solution used on its "Bulldozer", is the single fan, thinner radiator, and Intel-lighted branding.
What you get in the kit is standard fare for a self-contained liquid cooling solution. There is the main assembly that includes the pump/cooling plate, mounting hardware, radiator, and the flexible rubber tubes to carry the coolant from the pump to the radiator and back to facilitate the transfer of the thermal load from the liquid to the airstream provided by the single fan. The included manual illustrates how the cooling solution is installed and if you have installed one before it is all self explanatory.
The radiator measures 37mm thick at the edges, but the actual core surface is thinner and is closer to 28mm thick. The difference between the shell thickness and core thickness is there for a reason, to keep reasonable length fan and chassis mounting screws from penetrating the core liquid tubes. Fins per inch of core surface was 18. Looking through the core, you can see it is not restrictive in the least, allowing plenty of airflow. The overall dimensions are 180x115x37mm, making this solution an ideal fit in just about any chassis with a 120mm fan in the rear or top panels.
The Intel RTS2011LC low profile pump head and cold plate assembly are built using a proven design from Asetek. It receives some enhancements to the cold plate in the form of a more efficient micro-channel cold plate design to offer better cooling with less noise. The coolant mix is propylene glycol-based with most likely the same proprietary blending that Asetek has used in the past. Connecting the Intel RTS2011LC pump head to the radiator are a pair of extremely flexible rubber coolant tubes that are clamped in place. These tubes exit the pump head/cold plate via 90 degree swivel fittings for ease of placement. The rubber tubes are rated for a 50,000 hour life cycle. The Intel logo on the pump head lights up so you can show your loyalties. Power is supplied to the Intel RTS2011LC via a 4-pin connector. The fan attaches to the pump head via a 4-pin connection so both the pump and fan can be PWM controlled.
The custom designed blue LED 120x120x25mm fan used in the Intel RTS2011LC kit is rated to run between 800 and 2200RPM and push up to 74CFM. This fan is PWM controlled through the 4-pin power connection. At 800RPM, the fan is rated at a near silent 21dBa, while at full speed it carries a 35dBa rating. At the lower end, the noise level is near silent with other PC components making more noise. At full speed, the fan is audible, but no worse than the fans offered on competing solutions.
Rather than offer a fit that only works on a socket 2011 system, the Intel RTS2011LC is backwards compatible to sockets 1156,1155 and 1366. This means even if the solution looks attractive for a current build, you can use it now and later when moving up to socket 2011.
Good looks are not everything, however, and to see just how well the Intel RTS2011LC holds up under load, I decided to see how high the temperatures would get while overclocking. Using 1.45v on the core at 4.72GHz, the temperatures skyrocketed right on up and past 85 degrees Celsius after four minutes of testing. This shows that the thermal load at this level is a bit too much for the cooling solution. A bit more radiator and fan should help. The next quest was to find out at what speed and voltage combination I could reach Prime 95 stability and manage the thermal load. This turned out to be a much milder 4.5GHz using 1.325v. Still a pretty respectable number with a solution that would have an easier time holding the load with a processor that had fewer cores.
Holding the load at a high speed with a huge load is something that most solutions do not do well. Hence the need for liquid cooling solutions. Custom loops offer much better thermal performance, but an all-in-one will fit the bill even with the large thermal load. My goal was to find an overclock that would keep the temperatures in check and keep the load temperatures at or below 80 °C. In that respect, 4.5GHz was about the maximum speed attainable on this processor today. Intel's RTS2011LC is released into a crowded market with loads of liquid cooling "systems" on the market from Corsair, Antec, Cooler Master, and CoolIT. Of course air-cooled aftermarket solutions are available from the usual sources. Noctua has also released a kit to mount its line of heat sinks onto the 2011 socket.