do all mobo's support ECC RAM?

[aARON]

First of all, what is ECC? Does it give a substantial performance boost?
And do all motherboards support it?

[ghostface]

i think it has an extra bit for error checking. mostly important for servers and such when you can't have any memory errors that could cause a crash. i don't think it's any faster since all it adds is error correction. i want to say that you can use it anywhere but it's typically more expensive.

[Peter M]

ECC DRAM uses 72-bit wide data words instead of 64-bit. The extra 8 bit contain redundancy data (that are computed from the 64-bit data on write access) that allow (during reads) to detect multi-bit errors and silently correct single-bit errors in the 64-bit data that are fed back to whoever did the read. Ask your favorite computer scientist about the math behind that.

So what it brings is:

* more crashproofness in harsh (high radiation, high EMI) environments where DRAM cells might lose single bit contents noticeably often, or in high-availability server applications where any means are taken to push uptime percentage.

* SLOWER operation thanks to the extra computations needed on every read and write.

Today, almost all chipsets except those with shared-memory VGA, like Intel i810 and SiS chipsets, support it. On the latter chipsets, large amounts of data are permanently shoveled by the VGA unit, and adding extra ECC delays would make their remaining available DRAM bandwidth even nastier than it already is.

(Side note, neither does the i815 slap-an-AGP-port-onto-i810E patchwork. A major no-no for any kind of application where uptime is of relevance. Yet another point why i815 is no replacement for i440BX, let alone a match for VIA Apollo Pro 133A.)

Regards, Peter

[aARON]

Thanks! I'm glad i don't have to shell out the extra bucks for ECC. Now I just have to figure out if CAS 2 is worth it ...