Logo   Banner   TopRight
Date: Dec 14, 2001
Author: HH Editor
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)

EMS PC133 HSDRAM - Page 2

CAS2 vrs. CAS3 - The Test



(Our Test System)

Full Tower ATX Case w/ 300W PS, Pentium3 -450 Overclocked to 558 MHz. w/ a 124MHz.System Bus, Abit BE6 Motherboard, 128MB of Toshiba PC100 RAM and 128MB PC133 HSDRAM from EMS, IBM Deskstar 10GXP 10GB 7200 RPM EIDE UDMA Hard Drive, 3dfx Voodoo3-3500TV AGP Card w/ 16MB, Toshiba SDM1202 3rd. Gen. 4.8X DVD/32X CDROM, Win 98, DirectX 6.1


SiSoft Sandra "STREAM" Memory Benchmark

For this test we did not have a CPU in house that was capable of a 133MHz. Front Side Bus Speeds. Instead, we used a Pentium 3-450 that was capable of 124 MHz. with the utmost stability. In this test, the Toshiba PC100 module was not stable at the 124 MHz. bus speed at a CAS Latency Setting of 2, so it was set to 3. With this setting we experienced good stability with the Toshiba module.

However the EMS Memory was rock solid stable at 124MHz.X4.5 for a total 558MHz. with a CAS2 setting. What you see below is the difference that CAS2 makes with respect to system memory speed.

Click for larger view...


PC100 CAS3

EMS - PC133 CAS2

As you can easily see a CAS2 setting makes a difference and the stability of the EMS DIMM was perfect at this speed. Since the module is designed to operate at 133MHz. w/ 3,2,2 settings, 124 MHz. at 2,2,2 was a walk in the park for the EMS module. The Toshiba DIMM fell down badly even vrs. the Sandra base system. I can only assume the base system was running at 100 MHz. FSB and was set to CAS2. With this in mind it is easy to see how lower quality SDRAM can hurt your overclocked performance. Due to the fact that the standard SDRAM DIMM could only run at CAS3 with the 124MHz. FSB setting, we were forced to throttle back memory bandwidth significantly. This doesn't mean our P3-450 @ 558MHz. was slower overall than the base Sandra System, a P2 @ 450. The CPU speed boost plays heavily as well, of course. However, the system with a stable CAS2 setting at 124MHz. system bus enjoys the best of both worlds.


Wintune Memory Performance Test


PC100 CAS3

EMS - PC133 CAS2

Once again, a measurable difference between CAS2 and 3 and a measurable difference in memory subsystem performance.


Overall Impressions (updated 8/22)

I have seen a lot of memory modules and from my perspective, the stability and performance of Enhanced Memory Systems' PC133 SDRAM Module is second to none at this point in time. Other sites have tested this product vrs. other manufacturers like Samsung, who is noted for their high quality "-G8" chips. The outcome was the same. Nothing matched the HSDRAM from EMS with respect to stability.

Having said that, real world application performance will be impacted only by a small margin as a result of this higher speed memory. The real benefit this technology brings you is stability in extreme overclocked systems of today's technology along with some additional headroom for the next generation of bus frequencies with the latest chip set and processor technologies. At this point in time, the EMS HSDRAM is ONE of the fastest modules you can buy. There are other PC133 module makers out there and we will be taking a look at their offerings as well in order to level the playing field


We give the EMS PC133 HSDRAM DIMM a Hot Hardware Temp-O-Meter Rating of...



Content Property of HotHardware.com