On Tue, Sep 20, 2011 at 08:00:53AM -0400, Edward Ned Harvey wrote: > I can say this: ECC ram uses 9 bits instead of 8. This is not a simple > parity bit (because parity is only useful for detecting, not correcting > errors). But the payload is 8/9. Also, the actual error detection happens > off-chip, not inside the DIMM. That's why your motherboard needs to have > support for ECC ram in order to use it, and ECC ram is slightly slower than > non-ECC. Also, the volume of sales for non-ECC ram is much higher, so > non-ECC ram is significantly cheaper (not just a ratio of 8:9). > > So take it for granted, the non-ECC ram is significantly cheaper, and even > if you're using ECC, then the error detection is going to happen outside the > DIMM anyway.
This varies a /lot/ by density. I can get an 8GiB stick of Reg. ecc ddr3 for $96. for unbuffered ecc? (and I think the speed hit is on the buffering, not the ecc. unbuffered ecc, I believe, is about as fast as non-ecc) you are talking 4x that much. I don't know anyone that sells 8GiB non-ecc ddr3 at any price.. Of course, if 4GiB modules are enough for what you are trying to do, those are all great points. Just saying, I'm currently in a situation where buying registered ram is cheaper, not more expensive than the unbuffered stuff, and non-ecc isn't even possible. (I would be happy to be wrong; the LGA1155 xeons look really nice; the only problem is that they only support unbuffered ram, which means getting the 32GiB ram in there I need would require the ruinously expensive 8gib unbuffered modules) _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
