This month AnandTech makes another addition to the SDRAM test bed setup, using the latest beta PC133 modules from none other than the previous crowned champion, Samsung. Since the original review was published last month, the availability of the PC133 modules has not increased at all, however Enhanced Memory Systems' HSDRAM has finally hit the market and is available for sale. At $135 for a 64MB module, EMS has safely placed their SDRAM within the reach of only those that truly want to say that they have the most stable SDRAM available on the market.

Something only a small portion of the population will take into account is that the 133MHz FSB frequency is not a realistic goal for anyone that plans on using an AGP accelerator with any current Slot-1 motherboard. The reason? All currently available Slot-1 chipsets, including those from VIA/SiS, only allow for two possible ratios for the AGP clock frequency, those two being a 1:1 ratio with the system's FSB frequency, and a 2:3 ratio. Even when using the 2:3 ratio, the AGP frequency, at the 133MHz FSB, ends up at around 88MHz, or 33% over the specification for all AGP cards (66MHz).

Users have also provided the argument that purchasing SDRAM that is capable of running at 133MHz now would save another costly memory upgrade later this year when Intel officially introduces the 133MHz FSB specification with their upcoming Coppermine CPU. Unfortunately this approach is not too incredibly sound either, as there is no indication as to whether or not the Camino chipset (the first 133MHz FSB chipset from Intel) will even support today's SDRAM modules. The final decision boils down to how cheap and in what quantities Intel's preferred Rambus DRAM (RDRAM) modules are available in closer to the launch of the Camino. In the absolute worst case scenario, if the popularity of RDRAM is not as great as they are predicting it to be, Intel may be forced to adapt the PC133 SDRAM standard VIA has been pushing the industry towards. Although VIA will be shipping boards based on their 133MHz FSB capable Slot-1 chipset, the Apollo Pro 133 Plus, in June/July, owners of older PC100 SDRAM should rest assured as the chipset will most likely allow for asynchronous or pseudo-synchronous operation of the memory clock, an "extremely-VIA" feature that has been around since the introduction of the first Super7 motherboards.

With that said, it is time to take a look at how the PC100 champ stacks up to the rest of the competition when armed with a new, albeit pre-release, set of PC133 compliant SDRAM chips and a familiar looking PCB.

Preparing the Test

In order to isolate the memory modules as the only realistic causes of any fluctuation in stability, choosing the proper test bed was a bit of an ordeal, luckily AnandTech was aided in lab by the wonderful folks over at Kryotech who supplied AnandTech with a room temperature cooling system a week before the first stability tests were to commence. At the heart of AnandTech's SDRAM stability test bed was a Pentium II 333, capable of being reliably overclocked to 416MHz, running at room temperature with the aid of Kryotech's Renegade ATX-PE Room Temperature Cooler. The ambient case temperature of the Renegade test bed was kept at room temperature, or approximately 22 degrees Celsius, as was the surface temperature of the Pentium II processor.

The 333MHz Pentium II was chosen for its versatility in terms of clock multiplier support, as AnandTech's sample remained clock unlocked, and allowed for the usage of the 2.5x clock multiplier when testing higher FSB settings. In order to gain support for a wide variety of FSB frequencies, two motherboards were used as the basis for the test bed, the choice to use two motherboards came to make sure that there were no specific incompatibilities between the SDRAM being compared and a particular motherboard.

The entire test bed was configured as follows:

Due to popular request, the individual chip id's for each tested module are now provided as a release included with the test report.

The Candidates

The requirements for submission were as follows: All entries into the March 1999 AnandTech SDRAM Memory Comparison were to be made in pairs, and in configurations of 8 x 64 (64MB), 16 x 64 (128MB), and 32 x 64 (256MB). The modules must be available for sale within three months of the release of the article. So without further ado, we have AnandTech's top SDRAM candidates. (click images to enlarge)

Samsung PC133 Pre-Release Module	64MB
New Entry	64MB

Azzo PC133 Pre-Release Module	64MB
	64MB

Corsair Micron PC133 Pre-Release Module	64MB
	64MB

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Corsair SEC Modules	256MB
	128MB
	64MB

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Enhanced Memory Systems PC133 HSDRAM	128MB
	128MB
	64MB
	64MB

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Goldstar LGS	64MB
	64MB

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Memman Mosel Vitalic	128MB
	64MB

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Memman SEC w/ 3rd Party PCB

64MB

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Memman SEC Originals w/ SEC PCB	64MB
	64MB

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Mushkin Hyundai	128MB
	128MB

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Mushkin SEC w/ 3rd Party PCB	128MB
	128MB
	64MB
	64MB

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Mushkin SEC Originals w/ SEC PCB	64MB
	64MB

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Mushkin SIEMENS	64MB
	64MB

The Results

	100MHz FSB		112MHz FSB		124MHz FSB
	CAS - 2	CAS - 3	CAS - 2	CAS - 3	CAS - 2	CAS - 3
Azzo PC133	100%	100%	100%	100%	100%	100%
Corsair Micron PC133	100%	100%	100%	100%	100%	100%
Corsair SEC	100%	100%	100%	100%	86%	100%
EMS PC133 HSDRAM	100%	100%	100%	100%	100%	100%
Goldstar LGS	100%	100%	100%	100%	100%	100%
Memman Mosel Vitalic	100%	100%	100%	100%	0%	0%
Memman SEC1	100%	100%	100%	100%	86%	100%
Memman SEC Originals2	100%	100%	100%	100%	100%	100%
Mushkin Hyundai	100%	100%	100%	100%	80%	100%
Mushkin SEC1	100%	100%	100%	100%	86%	100%
Mushkin SEC Originals2	100%	100%	100%	100%	100%	100%
Mushkin SIEMENS2	100%	100%	100%	100%	80%	100%
Samsung PC133 Originals	100%	100%	100%	100%	100%	100%

	129MHz FSB		133MHz FSB
	CAS - 2	CAS - 3	CAS - 2	CAS - 3
Azzo PC133	0%	100%	0%	0%
Corsair Micron PC133	100%	100%	0%	100%
Corsair SEC	0%	100%	0%	0%
EMS PC133 HSDRAM	0%	100%	0%	100%
Goldstar LGS	0%	66%	0%	0%
Memman Mosel Vitalic	0%	0%	0%	0%
Memman SEC1	0%	100%	0%	0%
Memman SEC Originals2	0%	100%	0%	86%
Mushkin Hyundai	0%	86%	0%	0%
Mushkin SEC1	0%	100%	0%	0%
Mushkin SEC Originals2	0%	100%	0%	86%
Mushkin SIEMENS2	0%	86%	0%	0%
Samsung PC133 Originals	100%	100%	0%	90%

1 - Third Party PCB
2 - Samsung (SEC) Made PCB

The long overdue addition of the chip id numbers to the review should help straighten out some confusion, especially among the different types of Samsung modules. First of all, when purchasing Samsung based SDRAM, there are two different types featured in this review, the KM48S8030BT-GH and the KM48S8030CT-GH. According to Samsung's part numbers, the "B" in the first part number denotes a component revision number of 3, while the "C" in the second part number denotes a later, 4th revision of the chips. The Rev. 3 chips ("B") were found on all modules that were not Samsung originals, meaning they weren't originally manufactured by Samsung. The Rev. 4 chips, on the other hand, were only seen on the Samsung original modules, possibly contributing to the increased stability the SEC Originals offered over the competing Samsung based products.

The beta Samsung PC133 modules were a tad more stable than the older SEC originals at the 133MHz FSB frequency, unfortunately they did not remain crashless as the Corsair-Micron PC133 samples did during the tests. The stability of the modules can definitely be expected to improve as they grow closer to their final release date, the thing to remember here is that the force driving the need for PC133 SDRAM is not Intel, in fact, Intel won't be abandoning PC100 for around 6 more months, instead, VIA will attempt to convince the industry that the move to PC133 now, is a wise one. Can VIA accomplish the task? For their sake, we'd like to hope so, however until then, the sweet spot for any SDRAM purchase is still the 124MHz mark. If you can run at 124MHz, you should be fine with your current setup, there's no need to lose sleep over not having true PC133 SDRAM just yet.