Hi Beards,
I was using 3 HDSPe cards successfully in a Dell Precision 3500 with Xeon cpu (4 cores) and X58 chipset. When planning the system, I made sure I get the fastest memory and highest QPI system. I have good experienced with Dell Precision systems, they are much more expensive than your normal line of pcs but they are rock solid and my experience with them as DAW are simply very good.
Initially I had an issue with this setup where I would get crackles and noises as soon as the third card would be busy, no matter how many channels were in use in total, even if cpu usage was way down. After upgrading to the new beta driver, this phenomenon went away completely. The beta readme states "Optimized callbacks for multiple cards usage on multi-processor machines", I guess this is what solved the issue.
I am using over 20 input and over 20 output channels simultaneously for live recording & live mixing, this includes channel strip inserts on all audio channels, the system runs at lowest buffer settings because latency is an issue with live performance and the system is totally reliable and stable.
I am just converting to a Dell Precision T5500 with Dual Xeon cpu (3,34 GHz, 12 cores, 1333 MHz RAM, 6,4 GT/s QPI) to have more power available, but I can't report about this setup yet.
Regards, Mikael
2 DAWs, each C 7/64, W7/64, Dell Prec. T5500 (2 x X5690), 2 x rme HDSPe / Multiface II / Octamic II