One of the first things we'd naturally be interested in is how much memory throughput PC-1066 and PC-1200 are capable of delivering. We'll be using Cachemem to determine memory read/write speeds and as a means to verify Cachemem's results we'll be using SiSoft Sandra 2001's memory benchmark too.
Fig 5. The Cachemem benchmark results, notice how the i850-chipset scales nicely upwards with PC-1066 and PC-1200. Notice how these results are similar to the Sandra 2001 results below.
Fig 6. The Sandra 2001 benchmarks results show a similar picture as the Cachmem results, scaling upwards as the frequency is increased on the memory bus.
Upon looking at the benchmarks one thing is obvious, PC-1066 and PC-1200 RDRAM offers a significant increase in memory bandwidth. If we look at the Cachemem and Sandra 2001 results once more in terms of % increase, or decrease, in performance, where PC-800 is considered 100% we find the following:
PC-1066 RDRAM, 133MHz FSB
Cachemem Write Mb/s: (PC-1066/PC-800) = (1042.3/789.2) » 32%
Cachemem Read Mb/s: (PC-1066/PC-800) = (2405.2/1821.4) » 32%
Sandra 2001 Int ALU/RAM: (PC-1066/PC-800) = (1993/1508) » 32%
Sandra 2001 Float FPU/RAM: (PC-1066/PC-800) =(1975/1494) » 32%
PC-1200 RDRAM, 150MHz FSB
Cachemem Write Mb/s: (PC-1200/PC-800) = (1167.6/789.2) » 48%
Cachemem Read Mb/s: (PC-1200/PC-800) = (2693.9/1821.4) » 48%
Sandra 2001 Int ALU/RAM: (PC-1200/PC-800) = (2232/1508) » 48%
Sandra 2001 Float FPU/RAM: (PC-1200/PC-800) =(2213/1494) » 48%
From the above derived results we can see that PC-1066 is 32% and PC-1200 48% faster than PC-800 in both the Cachemem benchmark as well as in Sandra 2001’s STREAM benchmark. Keep in mind though that these are not real world numbers, in the next few pages we’ll determine just how much of a real world performance gain this increased memory bandwidth will offer for the Pentium 4.