Besides the overclocking experiments performed on Corsair Dominator TR3X6G1600C8D, we also wanted to find out if the use of DDR3-1600 SDRAM is overall justified for an overclocked LGA1366 system. That is why we are going to measure the performance of a system based on an overclocked Core i7 processor and DDR3 SDRAM with different latencies and frequencies.
We used the above described system with the Core i7-920 processor working at 4.0GHz frequency. The frequency was obtained as 20 x 200MHz. The processor L3 cache frequency was increased to 3.2GHz.
By raising the clock generator base frequency to 200MHz we could clock the memory at 1200MHz (with 6x multiplier) or at 1600MHz (with 8x multiplier). Overclockers working with a Core i7-920 processor will most likely face the exact same or very similar choice. So, our further comparison will show if overclockers will benefit from using memory kits like Corsair Dominator TR3X6G1600C8D, or if regular DDR3-1333 memory working at lower frequencies with 6x multiplier will not be a bottleneck for Core i7 based platforms. In fact, the answer to this question is not so evident, because the new Intel processor boasts a new triple-channel memory controller providing pretty high bandwidth and low latency even with slow DDR3 SDRAM modules.
First we ran a synthetic Everest Ultimate Edition 5.0 test that helped us determine the practical characteristics of the memory subsystem.
DDR3-1600 SDRAM does work at faster speed, however, the results differ not as significantly as we may have expected. DDR3-1600 with 8-8-8-24 timings shows no more than 10% advantage in read speed and latency (these are the most important parameters) over DDR3-1200 with most widely spread timings of 7-7-7-20.
This small but evident advantage of DDR3-1600 SDRAM shows in benchmarks based on real applications:
Complex CustomPC Benchmark based on real applications reveals minimal discrepancies during the tests of overclocked systems equipped with triple-channel memory working at 1200 and 1600MHz. However, the system equipped with DDR3-1600 may be up to 12% ahead of the DDR3-1200 rival in a multi-threaded benchmark, which is very sensitive to memory subsystem configuration.