Computer horsepower

[JeremyJo]

We're simplifying our services and need fewer channels now, though I added several monitor mixes to further spread things out on stage.

So we're using, around 40 input channels or thereabouts and 14 monitor mixers along with FOH.

I have two MOTU 2408 MKII and one 2408 MKIII for inputs with a PCI424 card. I normally run 1x64 sample buffer, 48K, 24-bit settings for the MOTU units. I would like to run 1x32 sample buffer to reduce latency.

Naturally when I switch to 32 sample buffer, the SAC load increases. At 1x64, our SAC load was around 40% rare dropped buffers. With settings at 1x32, the load goes up to just under 70% and when I add the FOH, wired remote computer I dropped about 15 buffers at once, though it seems to stabilize after a few seconds. Switching F keys quickly on the host/monitor computer, I get load around 80% briefly and a few more slipped buffers. I didn't hear any pops or crackles. I'll check during rehearsal with the band tonight. Couple questions:

How can I get the dropped buffers down, or stable with 1x32 and the PC I have? We're using a Core i5 with Sandy Bridge, Win7, 8G ram and SSD OS drive

How can I build a PC to do what I want, with 40+ channels, 14+ stereo monitor mixes, native limiter on each monitor output, EQ on several monitor outputs and three native reverbs on FOH? What is that hardware? Mobo? Video Card? Win 8? RAM?

When I run SAW Studio Lite I get a further increase in SAC load, which we're all aware of, but I also start dropping buffers pretty quickly - that's not acceptable. How can I stabilize the PC for that?

And I'd really like a SACRemote iPad app

Thanks

Jeremy

[Bob L]

I would suggest going back to XP... that most likely will give you the performance increase you desire... but I know you won't like that answer.

Another thought would be to drop the cores to 1 in the bios... see if that helps or makes it worse... then add a second core if needed... I would recommend not going beyond that if your cpu is showing up as 4 cores.

Once you are running past 70 or 80%, dropped buffers are generally going to happen on any multicore system.

You may just have to stay at 1 x 64 to keep your load under control.

Bob L

[Eric White]

Jeremy,

I have a motu setup like yours. during some testing I found that when I was trying to run at 32*1 , I would get dropped buffers when I would grab a screen window and drag it around the screen rapidly. Even the load number would flicker a little higher while doing this. Even when I would select "force single cpu" it didnt help. Sac was forced to a single cpu, but it was the first "0' cpu core. I opened the task manager, highlighted the SAC.exe process and manually set it to core #1 (second core) only. Seems like most windows processes that try to execute use up some time on the 0 core first. Immediately my system was stable at 32*1 and 0 dropped buffers even after a 24 hour run with winamp playing in the background.

Try this and see if it helps.


Good luck -Eric

[Mattseymour]

You don't specify which i5 you have. Is it quad core? SAC benefits from the fastest per-core CPU speed. So quad core costs you more and offers more general computing power but SAC can't use that...

You could try putting in the fastest clock speed sandy bridge CPU you can find and see if that helps.

There are real performance issues with Win 7 that are oft referred to. Some have found Win 8 to be better (although not as good as XP) but so far the systems I've installed it on have terrible DPC latency.

Speaking of which... What sort of DPC latency does your system have?