The ASUS OC Socket, present throughout the ASUS X99 mainstream and Republic Of Gamer motherboards, is a patent pending design modification of the standard LGA 2011-3 socket.
Haswell-E inherited the Fully Integrated Voltage Regulator (FIVR) design from the Haswell desktop platform, a component which splits one single input voltage into the voltage rails we’re been familiar with over previous CPU generations. In typical X99 platform implementations these individual rails, including VCore, VCCSA Voltage and CPU Cache Voltage, are effectively invisible to the BIOS and cannot be controlled independently. Overclocking and tweaking options have therefore been curtailed significantly with the introduction of an FIVR on Intel chips, preventing vendors from exposing additional control to enthusiasts and professionals.
This is where it gets interesting. Haswell-E CPUs have more contact pads exposed on the base than the previous generation of High End Desktop CPUs (IvyBridge-E and SandyBridge-E), but the pin layout of Intel’s LGA2011-3 socket specification is identical to that of LGA2011. In fact the major physical difference is the keying points, preventing non-compatible CPUs from being placed in the socket. What is the purpose of these pads, and what happens when you tap into them? ASUS wanted to find out.
When developing their versions of the X99 motherboard ASUS took the step of altering the basic socket to include 60 more pins, providing contact with every pad on the Haswell-E’s base, a design which is now known as the ASUS OC Socket. During the development process it was discovered that by exposing these contact points they were able to monitor voltages locked off in previous HED CPUs, past the iron curtain of the FIVR. In tern, this also allowed ASUS to improve stability for these crucial voltages and reducing the main voltage pumped through the CPU.
Interfacing with these points also allows improved stability when using the 166 strap (sometimes called 'gear ratio') on OC Socket motherboards. By utilising the 166 strap – essentially a series of configuration options to have the best possible system stability with a 166MHz BCLK - an overclocker can push the CPU frequency higher with a lower multiplier. In testing ASUS ballparked 4.2GHz as the highest CPU frequency on the i7-5960X when utilising the 166 strap on a basic LGA2011-3 socket whilst 4.8GHz was possible using the OC Socket, a 14% improvement. Enthusiasts will welcome this additional tweaking option.
Also unique to the ASUS OC Socket is a higher cache bus frequency tuning range than standard and higher voltage level control over cache bus voltages. In theory this has the potential to improve subsystem performance for improving specific benchmark results when small percentages are the target, but will likely have significant stability ramifications.
It’s also claimed that OC Socket greatly improves DDR4 memory overclocking. ASUS have been able to hit 3GHz at 1.35V, rather than the more typical 1.6V, and boast better high-performance RAM support. Furthermore DDR4 RAM tends to have a spike in voltage required at POST which trails over time, and ASUS have implemented a BIOS option called ‘DRAM Eventual Voltage’ to set a target for this trailing off and hence save power.
Last but not least is the raising of the Maximum VCore limit imposed by Intel. Not recommended, and certainly not for daily use, it’s the removal of a barrier at the extreme end of the overclocking spectrum where watercooling is old hat and even LN2 is pushed.
As you can see, the espoused benefits of OC Socket are very significant for the enthusiast overclocker, perhaps even more so for the professional. Headline figures, such as being able to push 5GHz on air and 6GHz under LN2 with minimal effort are certainly impressive, and the platform as a whole will still undergo a number of UEFI revisions during its life-time. The reality is however that your absolute overclock will very much depend on the 'silicon lottery', but ASUS want to assure you that their motherboards have the best chance of letting you push your CPU to its true limits.