A Mind Lost

A few weeks back I went through a round of upgrades and handing-down, where my father received my first-gen Core i5-750 and I upgraded to an i5-2500K.  The old computer has performed exceptionally since I put it together, with hardly a problem, and the old man doesn’t need the horsepower of a slightly more modern system.

The new machine has the aforementioned “unlocked” Core i5 2500K, stock clocked at 3.3GHz (with SpeedStep enabled), with 8GB of Kingston DDR3 1600 RAM at 1333, which is what the BIOS first set it to; I’ve not been arsed to bump it manually since the performance improvements would be so negligible as to be unnoticeable.  The motherboard is an ASUS P8P67 Rev3.1, featuring onboard sound, gigabit ethernet, and bluetooth.  Graphics are handled by a GeForce 460 GTX, and wireless connectivity by a D-Link DWA-552 wireless N adapter.  The graphics and wireless card previously inhabited the i5-750 machine, and worked without problems for over a year.

When watching a video, be it in Media Player Classic, VideoLan or YouTube, or listening to music with foobar2000, the interface will become unresponsive and the audio will buzz for about a second.  This happens frequently but inconsistently.

Searching for other folks with this problem, and hopefully a solution, didn’t turn up much until I came across a link leading to “the Sycon’s DPC Latency Checker“.  This program measures the latency of Deferred Procedure Calls (the link describes the concept in detail), where a problem free computer should produce output that looks somewhat like this (I am using the samples from Sycon’s site, I didn’t screencap my own use):

When there’s a problem, it looks more like:

While I wasn’t quite seeing such predictable spikes, I was getting high latency at intermittent intervals.  Determining the cause of the high latency, a poorly performing device driver, is to go through every non-essential device in Device Manager, and disable it.  After going through the first few that came to mind (the nVidia audio driver, Realtek audio driver, and Intel gigabit LAN), I finally disabled the D-Link wireless adapter and watched as the red spikes disappeared.

The suggested solution is to update the driver for the offending device and hope that the problem is fixed.  Unfortunately, the driver for this adapter hasn’t been updated since late August of 2010!

Instead I took a quick trip to a local computer shop and picked up an ASUS PCE-N15 wireless adapter (which uses a Realtek chip).  It took just a few minutes to swap adapters and plug everything back in.

So far I’ve watched an x264 720p video with DTS audio while writing this and maxing out my network bandwidth for about 45 minutes, keeping the DPC Latency checker in the background.  While it’s peaked at 721µs, it has remained in the green and the whole video played without a single stutter.

It’s odd that I never saw this behaviour previously with (almost) exactly the same hardware.  The D-Link never caused problems before (except for an issue when I was dual-booting to Linux).

The replacement adapter “only” cost just a bit less than $40 CDN.  I’ve read many accounts of people who recommend one stay clear of ASUS hardware, but after four motherboards, a DVD and BluRay burner, as well as an ASUS notebook, I’ve yet to encounter a significant problem.  Well, okay, they did ship the notebook with Windows Vista.  But aside from that, I’ve not had an issue with their products.