MIR requirements question re: new iMac

[dbudde]

Dietz, or anyone else who may know...

The new iMac comes with a 2.8GHz i7-860 processor.  The MIR requirements state i7-920 or better for smaller projects.  The 920 processor runs at 2.66GHz, but has a bus speed that exceeds that of the 860 (4.8GT/s for the 920 vs. 2.5GT/s for the 860).  So the question is, for the purposes of MIR running Windows 7 on an iMac will this be comparable to a 920 processor or significantly worse because of the bus speed difference?

[Dietz]

Bus speed is a significant paramter for a MIR-machine, no doubt. I will ask CM what he thinks of these new Macs.

That said, there are quite a few MIR users (especially  on Mac) whose machines significantly fail to reach our minimum specifications, but still they are happy with the handful of instruments they are able to work on in realtime. But officially we won't suggest an underpowered machine to you with a clear conscience.

Kind regards,

[DARC]

It also runs in dual channel rather then tripple channel RAM mode. The biggest difference between these two CPUs (and motherboard chipset P55 vs X58) is in sample performance. However the 860 is still a strong performer when compared to the last generation of Intel technology. I must add I have no experience of these Macs and if performance is effected much by powersave CPU features, it might not link directly up to peoples P55 based PC systems so you need to find someone who is actually using the iMac not just the chipset and CPU.

[cm]

a few (and incomplete) comments on memory configuration:

running tests for *raw voices* and using the demos zara & wondering why, we found memory latency, memory bus speed and number of memory channels to be the more important the more one puts stress on the CPU.

 

this is a non-linear relation between number of CPU cores, CPU speed, number of voices, number of instruments, (audio-)latency and number of output channels.

example #1 zara (22 instruments), stereo, latency 128 samples, 8 core 5550 @ 2.93 GHz, HT enabled

1066 = 39% CPU (crackles), 1333 = 34% CPU (no crackles)

example #2 zara (22 instruments), stereo, latency 256 samples, HT enabled

i7 950 (4 cores) @3.2 GHz, dual channel memory 56% CPU, X5550 (8 cores) @2.93 GHz, triple channel memory 25% CPU

 

in a nutshell: the closer it comes to the CPU limits the more important is memory performance.

we are still collecting data for a clear performance table and all figures you have for other configurations under controlled conditions are welcome.

christian