The 6Ghz speed is almost twice the speed of today's SRAMs. SRAMs usage is to hold frequently accessed data used by the processor. The faster the access, the faster the data transfer from SRAM to CPU.
Its been a long time effort for researchers to be able to overcome the process variability, especially variations that occur when a device is used in conjunction with other devices in an array making it possible for data to be lost. IBM researchers have come up with a novel hardware-based solution in order to reduce or even correct all problems problems and improve performance for various applications by using 8T SRAM arrays.