How do I get a consistant Latency?

I have a RealTek stock computer sound card. I have taken a double ended male cable and done the latency test exactly as decribed in the manual at least 20 times. The latency keeps moving around 5-15 milliseconds both ways. The average is falling somewhere around -170. I have the buffer set to the default 100. In the example in the manual they showed it being off 0.1 milliseconds but mine is off 5-15 milliseconds each time. I subtract or add this amount each time and test again and it is always off. Is this due to my cheap stock sound card? :question:

Probably yes.
Set it to the average value.
Unfortunately some cheap sound cards can drift quite badly, though for short recordings it may not be noticeable when you listen back.