HP X Class 500/550MHz hp visualize workstation - SDRAM Advantages with the HP - Page 2

Executive Summary The HP VISUALIZE X-Class Personal Workstation has been shown to have a significant performance advantage over competing systems when running technical applications. This is due to the HP VISUALIZE graphics accelerator, the system design and the new HP VISUALIZE Memory Architecture. This paper discusses how the VISUALIZE Memory Architecture contributes to improved performance. Drawing on the inherent advantages of Synchronous DRAM (SDRAM) technology, the VISUALIZE Memory Architecture has the potential to produce significant application performance gains for users of HP VISUALIZE X-Class Personal Workstations. These gains are made possible by the low latency of this SDRAM memory system. HP VISUALIZE X-Class Personal Workstations have posted a technical application performance advantage of almost 20 percent over competing systems. The HP VISUALIZE X-Class Personal Workstation is a Windows NT system that supports 133MHz SDRAM. The competing Windows NT workstation supports 800MHz RDRAM1. This comparison focuses only on the advantages of the lower latency that can be accomplished with 133 MHz SDRAM systems. It should be noted that SDRAM offers a significant cost advantage and a higher capacity. (For example today the largest capacity RDRAM RIMM available is 256 MB and the highest capacity SDRAM DIMM available is 512 MB.) The bandwidth of RDRAM systems (3.2GB/sec) is notably higher than the bandwidth of SDRAM systems (2GB/sec). But the additional bandwidth becomes insignificant when a memory system has significantly more bandwidth than the system bus can use. This was the case with the systems compared in the HP tests. With bandwidth issues negated, system latency becomes the primary reason for different application performance. Latency is a measure of inactivity. It is the amount of time that passes while a processor waits for the data it needs to carry out a processing task. Here, the differences between an SDRAM system and an RDRAM system are striking. The VISUALIZE Memory Architecture SDRAM system had 30 percent less total system latency than a comparable RDRAM system-or 97.5 ns for the SDRAM system compared to 140 ns for the RDRAM system. 1 The tested RDRAM system supported only four RIMMs. The system included no RDRAM repeaters. The importance of memory latency depends upon the application and the workload. When an application is using data in the CPU cache, the effects of memory latency are minimal. But when data is not held in cache, memory latency becomes a significant issue. In general, larger technical applications never run entirely out of cache memory, and therefore have inherent high sensitivity to latency. 1/5/2000 HP VISUALIZE WORKSTATIONS 1