ECC & EPROM…necessary or just a marketing trick?

Following Intel’s release of the LX chipset (everything seems to follow Intel’s release of a product) manufacturers began producing two new types of SDRAM: ECC SDRAM and SDRAM with onboard EPROM. Are these two types of SDRAM worth the extra $$$ it costs to purchase a module enabled with either or both of these features? This really depends on the type of user you are and the job the system will be performing. Error Correcting Code SDRAM (ECC SDRAM) is often necessary for server environments in which even the smallest error cannot be tolerated, however for normal desktop systems, gamers, or even professionals working in their home-office ECC SDRAM is NOT NECESSARY.

Then we move onto SDRAM with onboard EPROM…why on earth would you need EPROM on a SDRAM module? The technical answer to this question is that, onboard EPROM allows the modules to communicate with the chipset and in theory that enables the SDRAM to operate with more functionality and greater stability. The marketing answer to that question is simply that SDRAM with onboard EPROM is "better." What is the real world answer to that question? Here is an example of stability of SDRAM with onboard EPROM when compared to stability of SDRAM without onboard EPROM. Corsair Microsystems manufactures high quality SDRAM, however often times their modules are very difficult to obtain in Taiwan, where most of the motherboard research and development takes place and therefore manufacturers take for granted that their motherboards will function with Corsair’s high quality modules. Making assumptions such as that mentioned above can be deadly to your reputation. ABIT’s LX6, when operating at the 100MHz bus speed setting experienced random crashes and overall system instability when using 64MB of Corsair SDRAM (without EPROM). In order to eliminate some of this instability one must enter the BIOS Setup utility and take the SDRAM Latency Timing down to 3 (from 2) and disable SDRAM Speculative Read. However when using 64MB of Corsair SDRAM (with onboard EPROM) the user can easily run at the 100MHz bus setting with the BIOS timings set to their maximum level (SDRAM Latency Timing = 2; SDRAM Speculative Read = Enabled). Does this mean that SDRAM with onboard EPROM is worth the extra $30 - $90 per module? Decide on your own by considering the following example. Advanced Megatrends SDRAM, one of the most overall compatible types of SDRAM does not feature onboard EPROM and was designed months before the LX chipset ever went into mass production. Yet when using it on ABIT’s LX6 you can easily achieve rock solid stability (equivalent to that achieved when using Corsair SDRAM w/ onboard EPROM) at the 100MHz bus speed setting using the most aggressive BIOS timings.

Keep yourself in check…

So how do I know what type of SDRAM to buy? You may have heard people talk about certain types of SDRAM "chips" being better than others, they are usually referring to the physical chips on the SDRAM DIMM. And although they are technically correct in assuming that two identically manufactured memory chips from the same manufacturer will be equivalently reliable there is one thing they are not considering…something that can be summed up in 3 simple letters, P C B.

PCB, an engineering acronym standing for Printed Circuit Board is the physical board on which a circuit is printed (or etched) on. Even though you may have two SDRAM DIMMs both using NEC chips the PCB’s used with each module are completely different and could possibly determine whether or not the modules will work at higher bus speeds reliably, or even in pairs on some motherboards.

Quality in SDRAM doesn’t stem entirely from the chips used on the modules, although they do play a major role in the long-term stability/reliability of the module. Think of it this way, if you have a bridge with a roadbed that can hold 20 tons of weight what does it matter if the towers supporting the roadbed can only hold 5 tons? The same principle applies to SDRAM, if you have high quality NEC or SEC (Samsung Semiconductor) chips on a DRAM module what good will they do if you have a poorly manufactured PCB? The general rule of thumb when buying SDRAM is this, be sure to get genuine manufacturer produced modules, so if someone claims to be selling "Samsung SDRAM" be sure the entire SDRAM module was manufactured by Samsung not just the chips. With SDRAM, never settle for generic, if you find yourself in a tight money situation either wait or buy EDO because in the long run generic SDRAM will do more harm than good.

Ok…ok…I understand…but what brand of SDRAM should I buy?

It has begun... The Test
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