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DAX Pops and Cracks, Help with DPC issues

Hi All

So I am getting terrible pop's and bangs on RTTY and FT8 I have done some reading here and looked into the DPC issue,

I am running v3.4v.21 and have just done a persistence reset

I have a fairly high spec i7 13700k with 64gb of Ram and NVME M.2 SSD

I have attached the report from Latency Mon, Maybe someone here might be able to tell me something to try,

All the drivers are up to date,

What I will say is that the PC has never felt as fast as it should be, if that makes sense,







Your system appears to be having trouble handling real-time audio and other tasks. You are likely to experience buffer underruns appearing as drop outs, clicks or pops. One or more DPC routines that belong to a driver running in your system appear to be executing for too long. Also one or more ISR routines that belong to a driver running in your system appear to be executing for too long. One problem may be related to power management, disable CPU throttling settings in Control Panel and BIOS setup. Check for BIOS updates. 

LatencyMon has been analyzing your system for 0:06:21 (h:mm:ss) on all processors.




Computer name:                    DESKTOP-RT0NQP3

OS version:                      Windows 11, 10.0, version 2009, build: 22621 (x64)

Hardware:                       Z790 UD AX, Gigabyte Technology Co., Ltd.

BIOS:                         F4c

CPU:                         GenuineIntel 13th Gen Intel(R) Core(TM) i7-13700K

Logical processors:                  24

Processor groups:                   1

Processor group size:                 24

RAM:                         65374 MB total




Reported CPU speed (WMI):               340 MHz

Reported CPU speed (registry):            3418 MHz




Highest measured interrupt to process latency (µs):  181078.70

Average measured interrupt to process latency (µs):  17.919425

Highest measured interrupt to DPC latency (µs):    181075.0

Average measured interrupt to DPC latency (µs):    12.404976




Highest ISR routine execution time (µs):       3331.196314

Driver with highest ISR routine execution time:    Wdf01000.sys - Kernel Mode Driver Framework Runtime, Microsoft Corporation

Highest reported total ISR routine time (%):     0.005550

Driver with highest ISR total time:          Wdf01000.sys - Kernel Mode Driver Framework Runtime, Microsoft Corporation

Total time spent in ISRs (%)             0.005550

ISR count (execution time <250 µs):          354975

ISR count (execution time 250-500 µs):        0

ISR count (execution time 500-1000 µs):        0

ISR count (execution time 1000-2000 µs):       1

ISR count (execution time 2000-4000 µs):       2

ISR count (execution time >=4000 µs):         0




DPC routines are part of the interrupt servicing dispatch mechanism and disable the possibility for a process to utilize the CPU while it is interrupted until the DPC has finished execution.

Highest DPC routine execution time (µs):       51281.283207

Driver with highest DPC routine execution time:    audiodax.sys - Kernel-mode WDM driver, FlexRadio Systems

Highest reported total DPC routine time (%):     0.011369

Driver with highest DPC total execution time:     dxgkrnl.sys - DirectX Graphics Kernel, Microsoft Corporation

Total time spent in DPCs (%)             0.035393

DPC count (execution time <250 µs):          799867

DPC count (execution time 250-500 µs):        0

DPC count (execution time 500-10000 µs):       47

DPC count (execution time 1000-2000 µs):       7

DPC count (execution time 2000-4000 µs):       22

DPC count (execution time >=4000 µs):         14



  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator

    3.4.21 has an expired certificate in the radio. Upgrade to 3.5.9.

    Dave wo2x

  • EI2GLB
    EI2GLB Member ✭✭

    Hi Dave

    Thanks for the reply, I don't do remote so I don't think it is affecting my RX,

    Also I have heard that the latest version is causing more pops and cracks so I'm not sure if upgrading will help,




  • bahillen
    bahillen Member ✭✭✭

    3.5.9 release is working fine. Upgrade.

    An expired certificate will cause problems related to windows audio. Remote is not the issue.

    Try the update.




  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Trevor, as I understand it, SmartSDR continues to query the SmartLink server looking for candidate radios to connect to, even when not running remotely. 3.5.9 fixes this so that the server is not swamped and SmartSDR is not interrupted. This should prevent the audio issues. I upgraded to 3.5.9 and have no receive or transmit audio issues.

    So whether you operate remotely or not, you should upgrade to 3.5.9.

  • Gord-VA7GP
    Gord-VA7GP Member ✭✭

    I'm not really loving that high DPC latency, nor some of the Peak latency-to-process numbers (the averages look OK). Pops could definitely be related to these high numbers.

    You might consider Googling for thorough direction, but a good start would be LatencyMom and make sure you've got lots of low-numbers / light green. Your modern i7-13 CPU should be capable of awesome performance, but having too much "stuff" on your computer can be a DAX-killer.

    I've set up an older i7-6 computer for SmartSDR, and it's dedicated to Radio. No Office applications, no editing, All the usual Microsoft "Startup" stuff was reviewed and killed-off. It performs well. Using an nvme solid-state drive helps, but I am fairly sure you've already got that with your modern CPU.

    I guess I'm recommending a thorough check of your PC. Make it "lean" by removing anything not directly needed, stop any Cortana or other startup things not radio-related, After the PC, consider the connection between Radio and PC - even on a home-LAN you may have a flaky cable or cheap-o switch - perhaps a direct-one-cable-connection between radio and PC will inidicate if your network is OK or needing review.


  • EI2GLB
    EI2GLB Member ✭✭

    Thanks for all the replies,

    I spent a few hours trying various things I found across the net to reduce DPC latency and then to make W11 faster/leaner,

    I am not sure what I did but when my PC booted the desktop was flashing and I had no taskbar, I reverted the changes I made to startup and it was ok,

    Going to leave it alone for now,

    I did update to 3.5.9 and it is a lot better today, I am running SO2V with N1MM+ and it seems ok, but if I open DAX or Chrome there is some serious stuttering for a few seconds,

    I'm still not happy that this PC is as fast as it should be, but not sure what more I can do with it,

    Thanks again for the help, I see lots of posts about DAX popping so hopefully Flex will be able to do something to make it better for us all,




  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭
    edited September 25

    In my personal opinion, which I know is in a minority:

    1 As you say, FlexRadio should not be ignoring the ever increasing number of reports from users with crackles, pops and the like.

    2 After maximising hardware according to your budget, and if you are on Windows, streamline the OS. An eye-opener is a good network analyzer. Run it on your network to see all the data you are sending to MS like browsing history, One Drive, probes for WiFi, location tracking etc. These are a cause of audio hiccups as well as slowing the PC. A respected tool is this one:

    There will be the nay sayers who are adamant that the OS should not be "tweaked".

    I have an average spec computer running Swisslog, SDC, FRStack, StreamDeck, GridTracker, etc and on JTDX with maximum decoding settings I used to have some positive lag before changing to a 'debloated' OS. Now:

    negative lag of 0.50 seconds on around 50 decodes and still negative lag when decodes are 80+

    So, yes whilst I do think we are at the mercy of the SSDR software, there is always some remedial action for the user to consider.

  • EI2GLB
    EI2GLB Member ✭✭

    I spent some time trying to trim down W11 and ended up have to restore the PC, nearly lost my RTTY log as well, so I'm going to leave it alone for now,

    The upgrade to 3.5.9 seems to have helped,

    I'm currently doing a radio club challenge for the month of September to work as many DXCC's on 15,12&10 and I have limited my self to my back up 7300, so I'll play around more with the 6500 once that is over,

    Thanks for the reply Erik, hope you are keep well, chat soon,




  • EI2GLB
    EI2GLB Member ✭✭

  • EI2GLB
    EI2GLB Member ✭✭

    Hi Erik,

    I'm still struggling with slow performance so will have to try to improve things,

    I can get 80-100 decodes on a big pile up in the minus but if I try to do anything with the PC it cracks and pops, for example, I can not alt/tab to chrome while TX'ing FT8 if I do the output will jump and breakup, even clicking the windows button on the task bar will cause it to happen,

    I will make a video or 2 and post them, for the PC hardware I have there should be none of this, I built this PC to be a dream to use for the Flex and FT8 and so far I am very disappointed,




  • Graham999au
    Graham999au Member ✭✭


    I solved the same issues by ensuring the network card is not using any power management options - in particular Properties/Power Management/Allow the computer to turn off this device to save power. Make sure it is not ticked.


    Graham VK3GA

  • Erik Carling EI4KF
    Erik Carling EI4KF Member ✭✭✭

    Hello Trevor

    OK yes please make those videos and post the links here.

    Meanwhile, Graham VK3GA makes a good point. Follow FlexRadio's ethernet guide at https://helpdesk.flexradio.com/hc/en-us/articles/202118518-Optimizing-Ethernet-Adapter-Settings-for-Maximum-Performance

    Also Flex have Mike VA3MW who knows a lot about this and has posted many suggestions on the Forum so these are worth searching for. One big difference that I made was to to take his advice to upgrade to CAT8 ethernet cables (from CAT6). I had low expectations that this would make any difference but the cost of doing so was minimal so what the heck? Well, no more scratching as I tune and my only pops and crackles are from the known issues around SmartLink.

    So that's just a couple of things and I realize they not have anything to do with your trouble but just trying to help with suggestions as Graham did. I am sure the issue can be licked but getting to the solution is a PIA and I empathise with your disappointment.


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