DPC Latency - where do I go from here?

[outbackyak]

I ran DPC Latency Checker on my new i7 860 DAW, and it failed miserably:



I tried disabling the recommended devices, but it made absolutely no difference. I've disabled Realtek audio, the Firewire controller, the network adaptors, the floppy disk controller, and even my Novation ReMOTE LE keyboard. Even with them all disabled the DPC latency was unchanged. I have no internal modem or PCI or PCI-E add on cards.

So where do I go from here? Are there other devices that might be causing the problem that I could safely disable? If so, which ones? It suggests disabling USB host controllers, but how do I know which ones won't lock me out of using my mouse and keyboard?

So far I've not noticed any problems that are definitely due to DPC latency, but obviously I'd like to get this right. I have had unexplained input noise through my Fast Track Ultra audio interface, but I don't know if it's caused by the DPC latency or if it's a hardware issue.

Thanks!

P.S.: For system details see my signature.

[lodestar]

This may be relevant http://forums.tweaktown.com/f69/higher- ... ble-38168/.

Edit: You may want to consider updating to the latest F9 BIOS from here http://www.gigabyte.com.tw/Support/Moth ... =3238&ver=.

[b_rubenstein]

These latency issues are most often attributable to MB issues. The best forum for Gigabyte MBs is at Tweak Town (http://forums.tweaktown.com/f69/).

The bad news is that DPC Latency issues can be miserable to diagnose and fix. If you're lucky a new BIOS rev may fix it. Sometimes people just windup getting a different brand of MB.

(Ha! the two of us were writing responses at the same time.)

[lodestar]

BIOS settings can also be a factor. One which can make a difference is HPET (high precision event timer) which should be found on the Power Management Setup screen in the BIOS. Try setting this to Disabled.

[bonestonne]

Disabling CPC C-State (the Core i7/i5 equivalent of C1E) will help you out a lot.
Disabling HPET (as mentioned) will also help lower latency more.
sometimes doing a BIOS update will fix latency issues, sometimes it will make them worse.

In many cases, Wireless adapters and network adapters are the only devices that will be causing interference. Most computers today do not have a modem installed, nor can most people disable internal sound devices (as many people use onboard sound).

After seeing your rig in the gallery, I thought that interface looked familiar.

M-Audio devices are very susceptible power state changes, which results in latency spikes.

If you're running with onboard USB, I would suggest trying out several different USB ports, as I'm pretty sure USB controllers share resources with the PCI-Express bus. They wont conflict, but PCI-Express is much faster, and will therefore take priority. If problems persist, I would suggest a PCI-e USB card, as silly as it sounds, that might solve all the problems.

The drivers for all M-Audio products are being revised currently, but the issues are well known.

[outbackyak]

UPDATE: I also posted this question on KVR, and one person suggested I should try disabling Easy Tune 6, Gigabyte's performance tweaking tool, as this had cured his DPC latency problems with the same MB.

Seemed like the easiest thing to try first (I'm a bit paranoid about messing with the BIOS etc). Voila!



It's not perfect, but it's vastly better. I'll try some of the other tweaks suggested here and on KVR to see if I can get it down further, as it really should be down around 50-100 microseconds all the time.

Cheers!

[bonestonne]

Oh, yes, Easytune, I can never remember that problem because it's only on Gigabyte boards. That's been a known one for a while.

I can definitely understand not wanting to futz around with the BIOS, i only do updates on bright sunny days when the chances of any power fluctuations are slim to none. I can't afford a dead board at all.