Will a usb audio interface connect to a usb mic - I am looking to improve quality of recording rather than playback.
A usb soundcard is out of the question since it won’t connect to my usb mic.
No. A USB mic plugs directly into a USB port on your computer.
It seems that you already knew the answer. 
In most cases, changing the motherboard or even changing the whole computer will make no difference to sound quality.
The two exceptions to this rule are:
- Noise produced by the computer. Some computers have noisier fans than others, and some computers produce more electrical interference than others. As USB microphones are usually used quite close to the computer, noise from the computer may sometimes be an issue. In most cases, electrical interference will produce a low level whistling or buzzing sound, but usually this is so quiet that it is not a problem. Fan noise is more often an issue… more about this below.
- Faulty computer or faulty computer component. If your computer, or any part of it is faulty then recording may be affected. How it is affected depends on what the fault is. Typical faults are: gaps in the recording, severe interference, no sound in the recording, various error messages, computer crashes, Audacity does not open, the computer does not boot up. Other problems are possible. The solution to faulty computer problems is to either get your computer repaired or replaced.
Dealing with fan noise:
- The first thing is to place the microphone as far from the computer as is practical. Often this simple step is sufficient to reduce fan noise on the recording to an acceptable level.
- When recording voice, position the microphone and yourself so that you are close to the microphone. This will allow the microphone to pick up the voice more loudly so that other noises are relatively quieter. You may need to use a pop shield to avoid “pops” when you say the letters “P”, “B” and similar sounds.
- Speak clearly - don’t whisper. If the recording volume needs to be turned up high so as to pick up a very quiet voice, then it will pick up other sounds more loudly too (including fan noise).
- Make microphone recording in a quiet location with plenty of soft furnishing and/or other sound absorbent materials around. This will prevent sounds from bouncing around the room and will improve the clarity of the recording as well as reducing noises.
- Some sort of “acoustic shield” can be placed behind and around the sides of the microphone so as to cut down sound reflections and to some extent reduce unwanted external noise. This could be a simple home made affair or an expensive “microphone sound booth”. Search Google for ideas.
- For desktop/tower computers it is often possible to replace the fan with a quieter fan or other low noise cooling. This may need to be professionally fitted.
WARNING: Never cover, block or otherwise obstruct the airflow around the computer. Doing so can cause the computer to overheat and cause permanent damage and may pose a fire risk.
Please post a sample of the recording so we can hear what is wrong with it.
Have you made that overdub recording yet, so you can tell if recording with the USB mic and playing with Realtek makes the beat drift apart? Please do that and tell us the result before posting any more questions. If the tracks are not drifting apart then you may not need another recording device.
Gale
Ok I’m not going to mess with any other soundcards, motherboards or anything. And i’m not sure what made you think this - but computer fan noise is not an issue I have.
Also I’m not sure where I said anything was wrong with any of my recordings - I just want to improve the quality of my recordings and secure the settings i want to use before I record any more material.
I thank you for resolving my pitch problem but the issues I have now are separate to this problem.
If nothing is wrong with them, what is your concern?
We will not answer your questions again about “securing your settings” because we have answered them multiple times already.
If you have $1000s in the bank, why not spend it on new equipment, and see if you can hear the difference with the recordings you have now?
If you cannot hear the difference, and no-one else can, then you wasted your money.
Gale
If you had posted an audio sample then I would have known that.
As you haven’t I was covering possible issues that might make you ask about upgrading your hardware.
If there is nothing wrong with your recordings then don’t change anything. Few of us are able to achieve perfection, but if you have then keep going and don’t change a thing.