Audio Codec Buffer Underrun on Realtek ALC892
This error pops up on ASUS Z170 boards with Realtek ALC892. It's a buffer underrun – the audio chip runs out of data because Windows plays with power saving like an idiot.
What's happening
You're listening to music or playing a game on an ASUS Z170-A with a Realtek ALC892 onboard audio chip. Suddenly the audio crackles, pops, or goes silent for a split second. Then it comes back. This repeats every few minutes. The Windows Event Viewer shows error code 10 for the audio device – STATUS_DEVICE_BUSY. That's your buffer underrun symptom.
This happens most often when you're doing something that loads the CPU unevenly – like browsing with many tabs open while music plays. The audio driver tries to push data to the chip, but Windows power management yanks the PCIe bus to sleep state. The chip waits, buffer runs dry, and you get a pop.
Root cause in plain English
The Realtek ALC892 is a decent mid-range codec. But the motherboard's BIOS and Windows 10 power plan team up to do something stupid: they put the audio controller into a low-power state when they think it's idle. The problem is they're wrong. The controller isn't idle – it's processing audio. But the OS sees no activity on the bus for a few milliseconds and decides to save power. That takes maybe 10ms to wake up. In that time, the buffer runs from 64 samples to zero. You hear nothing or a crackle.
What's actually happening here is a race condition between the audio driver's buffer fill rate and the bus wake-up time. Realtek's driver doesn't tell Windows "hey, don't sleep my device". So Windows sleeps it. The fix is to tell Windows to stop that.
The fix – step by step
1. Update the Realtek audio driver
Don't use the generic one from Realtek's site. Go to your motherboard manufacturer's support page (ASUS, Gigabyte, MSI – whoever made your board). Download their latest audio driver. For ASUS Z170-A, version 6.0.1.8120 or newer works well. Install it, reboot.
2. Disable audio power saving in Windows
Open Device Manager (right-click Start → Device Manager). Find "Realtek High Definition Audio" under Sound, video and game controllers. Right-click it → Properties → Power Management tab. Uncheck "Allow the computer to turn off this device to save power". Click OK.
This is the most important step. The reason this works is because Windows now won't put the PCIe audio device into D3 power state while it's in use. The buffer never dries up.
3. Change the power plan – specifically PCIe link state
Open Control Panel → Power Options → Change plan settings → Change advanced power settings. Click PCI Express → Link State Power Management. Set it to "Off" for both On battery and Plugged in. Apply, OK.
This stops Windows from dropping the PCIe bus speed to save power. The audio controller sits on that bus. If the bus goes to L1 state, the controller can't send data fast enough. Setting link power management to off keeps the bus at full speed.
4. Set a custom buffer size in Realtek HD Audio Manager
Open Realtek HD Audio Manager (from Control Panel or the notification tray). Click the folder icon on the top right (Device advanced settings). Check "Make front and rear output devices play two different audio streams simultaneously" – this forces the driver to use a larger buffer. Apply. Reboot.
Not all Realtek versions have this option. If you don't see it, skip this step. The reason it helps is that with two streams, the driver allocates a bigger shared buffer, giving more time before it runs dry.
5. Disable Intel Smart Sound Technology (if present)
Some Z170 boards have Intel SST audio alongside Realtek. Go to Device Manager → System devices → Intel Smart Sound Technology. Right-click → Disable device. This stops Windows from confusing two audio controllers. Only do this if you use Realtek as your primary sound output.
If it still fails
Check your motherboard BIOS version. ASUS Z170-A with BIOS version 3401 had known audio latency bugs. Update to 3805 or newer. In BIOS, look for "Power Saving" settings – disable any CPU C-state lower than C3. Also check "DMI Link ASPM Control" – set it to Disabled. These are more aggressive power savings that affect the chipset's connection to the CPU.
Still popping? Try a USB audio DAC. Something like a Focusrite Scarlett Solo or even a cheap USB sound card bypasses the Realtek codec entirely. That's the nuclear option, but it works because USB audio has its own buffer management that doesn't depend on motherboard power states.
One last thing: if you overclocked your RAM or CPU, try stock speeds. Memory errors can corrupt the audio buffer. Run MemTest86 for a pass. One bad stick can cause intermittent audio issues that look like buffer underrun.
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