I've owned a DIY-built PC on a Gigabyte GA-EP35C-DS3R motherboard for about 2 years now. When I first built this PC, it ran perfectly under Windows XP 32-bit. Performance was good, and I had no issues with freezeups or audio distortion. I recently upgraded to Windows 7 64-bit, and since then, I've had serious performance problems. The system occasionally freezes up, usually for only a second but sometimes for more than 15 seconds. I get distortion in audio playback through the onboard Realtek Azalia HD-Audio, which sounds like the audio is frozen on a single tone for half a second or more, turning it into a buzzing sound. Video playback stops and stutters every few seconds as well. Disk and network performance are also significantly worse than under Windows XP. I get 2D graphics slowdowns drawing simple windows, like something out of 1995.
I've done research on my issues and found that they seem to relate to problems with driver DPC latency and hard pagefaults. I've been using the DPC Latency checker from www.thesycon.de/deu/latency_check.shtml, and I see frequent spikes of latency over 4ms. Baseline latency is rarely lower than 0.5ms, and is usually around 1ms idle, closer to 2ms when working. I've also used the Latency Monitor tool at www.resplendence.com/latmon , and it's reported hard pagefaults longer than 500ms, and DPC latency of over 2.3ms in netbt.sys.
I've tried disabling EIST and C1E in BIOS, and this helped a little bit. Disabling the onboard ethernet, sound, or USB also helps, but this is unacceptable, as I require all of these functions.
Before anyone asks, I've spent weeks ruling out other possible causes. I've malware and spyware scanned with four separate programs. I've chkdsked, defragged, cleared temp files, rebuilt page files, and swept my registry for errors with two different programs. I've disconnected every piece of hardware I could, checked every internal connection, checked my memory for errors with Memtest86+ for a whole weekend while I was out of town, run CPU burnin programs, swapped most of the cables, and even moved my RAID from the Intel Matrix controller to the GBB36X controller. I have a copy of Fedora 13 (GNU/Linux) on another boot drive which runs perfectly and extremely fast on this hardware. There's something about the way Windows 7 interacts with this motherboard.
I've seen that other similar Gigabyte P35 motherboards have had this issue, and some have been helped by BIOS updates.
I have the latest BIOS for my motherboard, which does not appear to have had an update from Gigabyte regarding this issue. I've filed a ticket with them in hopes that they can help.
Does anyone have any suggestions to how I might recover? I really don't want to roll back to Windows XP!