Fix for stuttering/performance problems

[hal900x]

This will resolve many but not all stuttering and related issues, especially if you have an Audigy card or play Battlefield, UT and others. It took quite a bit of study to find it, so I offer it to the community as a possible solution. This fix works for any video card, but especially applies to Radeon and Geforce owners (all models). You implement this fix at your own risk and I accept no fault whatsoever for the consequences. I have never experienced any problems arising from it.

First, you need Powerstrip from www.entechtaiwan.net/ps.htm It's free although I highly recommend purchasing it, it's one of the best software tools out there for tweak freaks. Install it and run it. You'll get a prompt at first run to accept your adapter defaults. For the purposes of this fix you can just click OK, but Entech recommends you reset your video card to Adapter Defaults before accepting this dialog.

Once powerstrip is running it will be in your taskbar. Right click it and choose Options/Adapter information. You will get a window with all sorts of good info on your Video Card. Uncheck the "Read Only" box. After this point be careful not to change any other settings that the one I describe below.

One of the settings you can now alter is "Latency". Normally this will be set to 248 on most cards. Use the little up/down arrows next to this value to set it to 64. Hit the "Apply" button to accept the change. You will be prompted with a couple warning dialogs the first time you do this. Accept them both by clicking OK. Now, by clicking the larger up/down arrows in the upper right hand side of the window, you can scroll through all PCI/AGP devices in the system. Make the exact same change with every device in the list, clicking "Apply" after each change. Some devices will be greyed out or hardcoded and cannot be changed. That's fine, keep scrolling through the list and changing any that will allow it to 64. When you are done, click the OK button. A reboot might be necessary at this point, although I don't need to.

Now check and see if your issue is resolved. Reboot if necessary.

Now, if you are not satisfied with the results try repeating the process with a different value. Try 32 for your second time through. You can experiment with different values, but the important thing is to make sure all values are identical for every device in the list.

Feedback on the success/failure of this method is appreciated. I'll explain exactly how & why this works in a later post. Enjoy!

 

[Nazo]

You sure it's not just the soundcard operating at a lower latency that corrects the problem?

Anyway, I'm curious if that kind of thing might actually speed things up. I think I might run a test or two. In theory lower latency makes things run better, but of course there are exceptions. (For example, my memory works just fine at 2-2-5-2, but it's just slightly faster at the 2-2-6-2 which it was rated for.)

EDIT: Oh, and you should remove that period from the end of the URL. It sends you to some weird site that's completely unrelated.

 

[hal900x]

AGP and PCI are on the same bus for the purposes of this fix. Don't want to get too deep into that end of the discussion, but here's the rest of the story on the fix:

Here's a layman's guide of how PCI Latency applies in this case. Think of Latency as a timeslice: The higher the latency value, the longer that particular device has the CPU's attention. The PCI bus moves in a loop from one device to the other, and when the last device has been given some time to perform it's function, it begins the loop again. So, for example, if the video card has 248 cycles of PCI latency and the sound card has only 32 cycles allotted, then the video card is going to be hogging the PCI bus much longer than the sound card. The problem is that the PCI specification was designed to have similar latency values for all devices on the AGP/PCI bus. In fact many BIOS's have a "PCI Latency" adjustment. Unfortunately this BIOS setting rarely applies to all devices on the PCI bus. Powerstrip covers them all, fortunately.

The problem is that the PCI specification allows device drivers to override the default PCI latency of the bus. So even if your BIOS is setting it to, say, 64 for all devices, your video adapter driver is hogging the bus's cycles by overriding this value to it's highest allowable setting, 248. Why would ATI or Nvidia, for example, do this? Well, that's pretty simple: Benchmarks for one. They are also ensuring plenty of bus time, no matter the consequences, for their card to perform it's complex functions. Unfortunately when other cards (especially certain sound cards) depend on roughly equal timeslicing, the often cause the system to "Hiccup" while they catch up. Audigy cards in particular cannot handle inadequate PCI cycles. It's more noticable in games that demand a high FPS like Battlefield.