This turned out the be a long post, the purpose of which is almost more to document my tests rather than ask a question. Feel free to read it and come with suggestions though.

I have an issue where I can't seem to find a microphone to my computer which doesn't require the setting "mic boost" to be turned on. It basically increases the signal by quite a bit, which of course also increases the level of the noise (and probably introduces some other negative aspects regarding clipping and similar.) I am not even looking for great quality regarding input, decent will suffice.

I have a motherboard with integrated Realtek sound card with terrible SNR. When the amplification is increased the noise becomes unbearable.

I also have an Xonar Essence STX with great SNR, basically silent. With mic boost, the noise it remains pretty quiet but another problem which is different occurs. It picks up an interference from the GPU, which sounds very different to the typical baseline noise. I have found out that this issue is very common because the STX only has EMI shielding on the output section, and not the input. It even occurs in other several other Xonar cards.

Sound samples from other people which are similar to mine: Sample A , Sample B

What I have tried:
I have through a few tests established that the interference comes from the GPU and is tied to the amount of frames per second it renders at. It is not affected by temperature, fan speed, brightness or load of the GPU as a few have suggested. This testing has been quite extensive.Below is a list of suggestions I have found and tried:
-If I use the setting "frame limiter", it naturally limits the frequency of the interference since it limits the FPS but doesn't decrease it. Slightly less annoying that it at least stays more constant.
-Moving the STX to a PCIe slot further from the GPU decreased the noise a bit. This indicates to me that the interference travells through air or PCIe lanes as these distances increase. It does not travel via the PSU since that distance remains the same in this case. This is also the reason why I haven' soldered extra capacitors to the power connectors as some have tried to try and filter out noise travelling from the PSU.
-C1 and Speedstep settings in BIOS does not affect it
-Different drivers, even the open source ones, does not affect it
-Mic level and mic boost of course amplifies it along with the rest of the signal
-Ungrouping all inputs into separate ones and disabling the rest does not affect it
-I didn't use the front panel headers to begin with, but they don't affect it
-It is not affected by the output stage of the STX. Using an O2+ODAC for output yields no difference on the input of the STX

Things I haven't tried yet:
-Soldering capacitors to the power supply, as explained why above.
-Replace PSU
-Replace motherboard
-Replace GPU
-Extend the EMI shield of the STX. Perhaps even cover it all in sheets of insulated aluminium foil.
-Try and insulate the cards STX's PCIe bracket from the case
-Ground the GPU and STX by scratching the paint of the case a bit. The screw for the PCIe bracket should ground it already but more is better.
-Add extra grounding to case from PSU, to other ground sources, as grounded sheets in PCI ports in between etc.


If I could find a mic which gave high enough levels for mic boost to not be required, or if I could solve the interference issue things would be great but it appears to require some major change. At this point I gave up on it, and 6 months later I built an O2+ODAC. I got it to replace the output of the STX as it seemed like a more flexible solution since I can get any ADC+mic solution I want without being locked to using the input of the STX if I use its output. I have a Logitech table mic, a Zalman clip on cable mic (some call it fly mic), a ball microphone I forgot the brand of and at least two headsets.

I don't think I should be required to replace some major part of my computer and I am a bit hesitant to mod my STX to much. This is why I am looking elsewhere for solutions. Alternatives:

STX + sensitive mic
STX + proven combo of mic and a cheapo external soundcard
O2+ODAC + proven combo of mic and a cheapo external soundcard
O2+ODAC + integrated soundcard and a sensitive mic
New external high end USB sound card with amplifier, DAC and ADC to replace all

Here is a review of the ModMic where the guy suggests a cheapo USB sound card which he appears to get very decent results from. I should be getting similar results with that combo since it is connected via USB. I could even use an USB extension to bring it further from the source of the interference. I think we have ruled out the +5V of the USB to carry any interference since it doesn't pass via the PSU. This combo could be a candidate for the "proven combo of mic and cheapo external sound card". The ModMic is said to be sensitive and some say it even works with the STX directly while others say it doesn't. Either way, I am probably going to get one for testing purposes.


This was extensive, and I assume very few have read to this point. If you have, I would appreciate any suggestions you may have.

Roland Tri-capture and your choice of external XLR mic.

I forgot that I have considered getting a new external high end USB sound card with amplifier, DAC and ADC to replace all. I have also considered something which requires a mic preamp. As I stated earlier though, I would rather get a passing input and focus on the output. I'd rather avoid having to get a very expensive setup for the input. If it is included in a nice output as in your case and many other external solutions then I can let it pass as it could replace everything.