Why do some MBs require registered RAM?

TimTim Southwest PA Icrontian
edited January 2006 in Hardware
I've been looking on eBay for dual CPU motherboards, mostly dual Athlon setups, and I've noticed that a lot of the boards reuire registered RAM.

Why is this? What's so special about registered RAM? What would happen if I put in regular SDRAM / DDR RAM?

I've had an Abit VP6 and BP6, and they took regular SDRAM memory, nothing fancy.

I've seen some Tyan motherboards, like an S2518, Tiger S2460, S2462, S2518GNR, and S2466 that all say they need registered RAM.

The Asus A7M266-D says it can take 3.5 GB of registered, or 2 GB of unbuffered RAM. I'm not sure if "unbuffered" means regular DDR RAM or not.

Comments

  • csimoncsimon Acadiana Icrontian
    edited December 2005
    yeah unbuffered is regular ram you could say.

    You can do a search on ECC and registered (buffered) ram and basically it is a more stable ram. Usually it is required when you have a quanatity of ram sticks such as 4 or so ...It is slower because of the error correction but it is most stable.

    Hope that helps.
  • muddocktormuddocktor
    edited December 2005
    Registered ram is just that; it has a row of registers that keep signal level up (that's what I understand at least, I'm no electronics expert) so you can run more sticks of ram. The reason that the old dual AMD boards require registered ram for more than 2 slots to be occupied (or in the case of Chaintech or Tyan, registered needs be used regardless of how many sticks you run) is due to the use of the AMD762 northbridge, which is based on the original AMD761 northbridge, which was the first chipset for ddr for Athlon. I guess they were going for max stability on the chipset and also maybe their design team was just trying to make sure they got everything right so there wouldn't be any bad problems crop up on initial release (like most all of Via's early chipsets).
  • TexTex Dallas/Ft. Worth
    edited January 2006
    Tim wrote:
    The Asus A7M266-D says it can take 3.5 GB of registered, or 2 GB of unbuffered RAM. I'm not sure if "unbuffered" means regular DDR RAM or not.

    I have owned four or five of those boards. You can USUALLY get away with up to TWO sticks of really top quailty (not cheap or generic) regular ddr. But look around at someplace like the forums at 2cpu.com and tons of folks had instability running corsair, crucial, mushkin etc... that cleared up when running registered memory. You might get it running OK but trust me here.... I have built at least a dozen of the old MPX chipset boxs and you want to get registered DDR to keep probs to a minimum.

    Now that I have that said.... why in the name of gawd would you put money into that old dated chipset? For not much more on eBay you can get a low end opteron and you know.... have a board and cpu's with a warranty and everything. I RMA'd so many MSI and ASUS mb's based on that chipset it was unreal.

    Tex
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