Cheap DDR3; can ECC memory be used with ECC off?

[Nohbdy820]

So, I've been researching about building a computer for a while now, and with DDR4 prices not going to drop for a while, I've been looking at used ddr3 to go with an older CPU and motherboard: specifically an i5 3550 or 3570. If you look on eBay, you can find really cheap dimms. Like 8gb 1600mhz for $25. But, the memory is ECC memory. While looking into compatibility, I've found multiple answers that aren't helpful. Apparently ddr2 was very different between Server and Desktop, but ddr3, not so much. And ECC can be turned off, to not use the extra "core" or something. Others were answered: "Why do you want ECC ram? You don't need it, plus its more expensive". Which didn't answer the question of compatibility. Also, some desktop mobos do support ECC, so answers were given as such.

So, is ECC ddr3 ram exclusive? Or can you use it without the feature on normal desktop hardware? And if not, why?
Link to example:
http://www.ebay.com/

 

[Kasper Jorgensen]

Sometimes it will work and sometimes not. It's hard to tell if those Exact RAM will work with your exact mobo. Better to get some normal DDR3 ram instead of taking the chance.

 

[Windwalker95]

Most likely not.

 

[BFG-9000]

Sure, ECC unbuffered memory will work fine in non-ECC mode in a motherboard that doesn't support ECC.

But that memory won't work, not because it's ECC but because it's registered.

 

[Nohbdy820]

Sure, ECC unbuffered memory will work fine in non-ECC mode in a motherboard that doesn't support ECC.

But that memory won't work, not because it's ECC but because it's registered.

Ok, I think I understand a little better. The "register" is the "extra 'core' or something" that I heard about, which isn't always built into ECC RAM. It disallows all desktop mobos from using them as it is a feature developed specifically for server mobos. And buffered and registered RAM is the same thing. Thanks for the response!

 

[BFG-9000]

Yep, unbuffered ECC is expensive, and the cheap stuff is all registered/buffered. It's cheap used because virtually nobody can use it.

Memory controllers can only handle a certain number of address lines, and the buffer chip takes over some of this load itself so can use more (which takes time so is why there is a performance hit with registered). A memory controller not designed for a buffer chip isn't going to know what to do with it and can't see past it because the chip's function is to hide the actual configuration of address lines from the memory controller.