48 GB RAM 1333 MHz in flashed Mac Pro 5,1 working as 1066 MHz

[Spacedust]

Interesting. About the memory controller change with Westmere, would that have been done in firmware or was it a different chip?

BTW, what channel are DIMMs in MP slot 4 or 8 on? Do they share a channel with another slot?

Yes, then you got dual channel only. That's why we all use 3,6,12,24,48 or 96 GB RAM

 

[macmesser]

Yes, then you got dual channel only. That's why we all use 3,6,12,24,48 or 96 GB RAM

Thanks. I get it now. Just first three slots for triple channel, otherwise it regresses to dual channel. Any idea as to how much faster over dual channel triple channel is?

 

[Umbongo]

Thanks. I get it now. Just first three slots for triple channel, otherwise it regresses to dual channel. Any idea as to how much faster over dual channel triple channel is?

It's all negligible. You will only notice it on benchmarking tests.

 

[cmonneron]

Reset PRAM.

worked for me, so not useless to try