Devices on PCI bus?

[Deders]

Would anyone know what devices run off the PCI bus that would be affected by the latency timer on a p55 GD65 or similar.

Is it just the PCI cards or does it include things like USB or Firewire?

If I go into Device manager and view by connections, pretty much everything that isn't the CPU, (or that was visible before I started expanding the list) Is listed under PCI Bus.

 

[Bernhard]

Refer to this link http://techreport.com/articles.x/17513 , which pretty much lays it out quite nicely. A web search for P55 chipset will provide you with a host of links and information.

 

[Deders]

I have searched and most articles I've read don't seem to have any info on what is probably the least exciting part of the P55 chipset.  There is plenty on PCI express etc but nothing on PCI itself.

If my X-FI is the only thing on the PCI bus then it's probably safe to set the latency up to 128 so it doesn't de-couple with the bus to allow other devices to use it as often.  On the other hand if there are other devices that are using it, then 128 will be making them wait too long leading to less than optimal performance.

 

[dsp4live]

I can tell you the latency differences between 64 and 128 are unnoticable.
What is most important for a 32bit PCI soundcard is the Interupt Requests.
If you know how to re arrange these and delete unnecessary devices, you can get better results free from clicks and pops associated with realtime needs of audio.
I have PCI-e 1X audio and 32bit PCI audio and the best results come from isolation and giving audio its own IRQ.

I was surprised at the MSI X58A GD-65s' ability to share the video card on the PCI-e 1X audio card and work flawlessley.
It's a first for me, but it seems the X58 chipsets, even being a lower binned version of the 5000 Xeon series, are great audio chipsets.

Check your IRQ's for the fix though, the latency settings really show no difference.
I have guys running 3 x 32bit DSP powered audio cards so they can have excessive I/O's and MIDI, and as long as the video card and audio are isolated, there's zero issues.

 

[Deders]

Interesting info thanks, how isolated do the Video and Audio need to be?? I did have trouble with skipping sound at one point but thats been fixed with a bios update.? I do get pauses in some games though.

Just checked my IRQ's and IRQ 16 has both video cards as well as both of the CPU's PCIe ports, which seems ok as they are connected that way but one of the USB controllers is also on 16.? Should I move this?

The soundcard shares IRQ 17 with the motherboard's PCIe port 1 which has the onboard network controller connected to it.

IRQ 18 has the motherboard's PCIe port 3 sharing with the OHCI controller which I presume is the firewire port that i'm not using at the moment, but I keep it on in case I want to connect something.? These are both listed in device manager as being connected to each other.

IRQ 19 has the standard IDE controller which is connected through the motherboards PCIe port 4 (also 19) and both the 4 port and 2 port Sata connections.

I seem to have IRQ's 2, 3, 5, 7, 10, 12, 14, 15, 20, 21 and 22 completely free.? How many of these do you think I should seperate considering the CPU's PCIe ports are one 16x port divided into 2 8x?

 

[dsp4live]

Just look at what you might not need and disable it in the Device Manager.
There tons of gunk in there.
This also clears the way for a more efficient interupt latency template.
I chose to remove the Marvel RAID, USB 3.0, and the SATA 6GB ports.

http://www.thesycon.de/dpclat/dpclat.exe
http://www.thesycon.de/dpclat/dpclat.pdf

This little tool might be helpful once you get your interupts situated.
As long as you remain below the 600us.
I am a live performer and prefer using an external PCI-e 1X connected DSP rack for my soundcard.
I need 1msec@96k and Native solutions cannot provide the power I require. The OS and additional layers of crap from Apple and M$ are not my idea of a pro solution, so I have used DSP solutions for 15 years now.
But I still need the lowest latency I can get.
I chose the MSI since I didn't need my coffee made for me, just some sweet spot OC'ing and the Meat & Potatoes.

In my experience the more pipes one has the larger the risk asessments.

 

[Deders]

handy little app there, thanks.

I've gone through everything that can be disabled that isn't vital to the system and I'm still getting occasional peaks in the graph of about 600, most of the time it's below 120, sometimes it spikes at around 1100.

Unfortunately because I'm using ACPI which leaves all IRQ routing to Windows, there's nothing I can do to change the IRQ's, even though ACPI can supposedly change IRQ's on the fly, windows doesn't give me the option.

It does make me wonder why they are made to share even though there are clearly plenty of spare ones.

AMD suggest that next time I reinstall, I start with the minimum needed to install and then add hardware one at a time.  I might try this one day but I'll just have to suffer for now unless anyone has any other ideas....?