Question about registered DIMMs

[KoolDrew]

I'm not quite sure about this so I thought I'd ask. Some processers (eg. AMD Athlon FX-53) require ECC Registered DIMMs. I know this can slow down memory access speeds. But if you were to use ECC DIMMs with a processor that doesn't require them would memory access speeds be the same as if you used non-ECC DIMMs?

 

[Matthias99]

There's a difference between "ECC" and "Registered ECC". Registered RAM will *only* work with a controller that supports registered memory, and generally vice versa (for instance, the Opterons cannot use regular RAM; it has to be registered). If you use non-registered ECC RAM on a memory controller that does not support ECC, the extra ECC bits will be ignored.

*Generally* Registered/ECC RAM has slower timings than non-registered/ECC RAM, but at the same timings there should be no speed difference.

 

[TerryMathews]

Originally posted by: Matthias99
*Generally* Registered/ECC RAM has slower timings than non-registered/ECC RAM, but at the same timings there should be no speed difference.

Negative. The registered (sometimes referred to as buffered) memory is one CAS cycle slower than unregistered or unbuffered memory. CAS 2 registered == CAS 3 unregistered.