EMS PC133 HSDRAM - Page 1



The gating item. Something that renders everything else dependent upon its outcome or performance. The type of SDRAM (Synchronous Dynamic Random Access Memory) you have installed in your PC weighs heavily on the overall stability of your system and the various other components that rely on it. These include just about every other device in today's X86 based computer. For this article we are focusing on SDRAM since it is the mainstream base memory component used in today's PC. Older technologies such as EDO DRAM and Fast Page Mode still exist in some computers but all new systems are designed with SDRAM now. Future generations of memory, such as RAMBUS and DDRAM (Double Data Rate SDRAM), are forthcoming with newer chipset technologies but there is still some life left in SDRAM.

In addition, there are a few types of Memory Modules that have evolved from the SDRAM chips themselves. The original SDRAM Modules made were specified to perform at a system bus speed of up to 83MHz. Then came PC100 Modules. You guessed it, 100 MHz. Recently, a couple of manufacturers have brought to market PC133 SDRAM Memory Modules.

These SDRAM Modules are designed to operate at a memory bus speed of 133 MHz. and higher. The good folks at Enhanced Memory Systems, were kind enough to send us one of their 128MB HSDRAM PC133 Modules. HSDRAM stands for High Speed SDRAM which I assume is their own acronym. Here are some of the features that make their product different.

(click for a closer look)

  • Fast 4.6 ns Clock Access Time
  • Lower Latency Than Other PC-133 Modules (3:2:2) @ 133 MHz
  • CAS Latency = 3
  • RAS to CAS Delay = 2
  • Precharge delay = 2
  • High Quality 6-Layer PCB for System Stability
  • Uses 64Mbit Enhanced Memory Systems Chips for Consistent Performance
  • Overclock Existing PC Systems to 133 MHz
  • On-board Serial Presence Detect (SPD) EPROM
As you will note above, the Clock Access Time otherwise known as Clock To Data Out is 4.6 ns. This is on average about 24% faster than the typical High End PC100 SDRAM Module. A PC100 Module, with decent discrete chips on it, will have a tAC (or clock access time) of 6ns.

In addition, the latency specs such as CAS (Column Address Strobe) and RAS (Row Address Strobe) are less than most SDRAM chips on the market today. As you can see 3,2,2 for CAS Latency, RAS to CAS delay and Precharge Delay, respectively. Most other SDRAM types at 133 MHz. clock speeds, need to be run at least in 3,3,2 mode and sometimes 3,3,3,. What does that mean to your system? Well, simplified, this means you have less latency (less latency good/more latency bad) or fewer useless dead clock cycles before your CPU can read or write to the memory. In a nutshell, FASTER. In additon, these SDRAMs are rated at 7.5ns Clock Cycle Times, which means they are slightly faster in general than most 8ns. SDRAMs used on current modules.

The EMS modules should, for all intents and purposes, be faster because they can run in 3,2,2 at 133 MHz. and also be more stable at that speed because of faster clock access times which allow the delay timings more slack on a clock cycle. So, you're thinking "prove it", right? That's what we're all about here at Hot Hardware. Let's fire up Ol' Besse and take a look,shall we?

 Testing 1, 2, 3.... --------> (next page)

Tags:  RAM, PC, SD, DRAM, SDRAM, MS, c1, AM

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