Well...  I've come to the determination that this must be some kind of hardware compatibility or fault issue.  I re-flashed the BIOS that made no change, so finally in desperation I did a full format and install of windows 10, and am still facing the same issue.
Just to be sure I wasn't crazy I dug out an old laptop running Win 7 and ran pingplotter on it simultaneously with the problem desktop.
Here is the results form the old Win 7 laptop;
Target Name: att.com
         IP: 144.160.155.43
  Date/Time: 4/14/2018 3:12:43 AM - 4/14/2018 3:22:43 AM
Hop  Sent  PL%    Min      Max     Avg  Host Name / [IP]
  1   244    0   1.00  1382.00    9.18  attwirelessinternet.wirelessi
 nternet [192.168.1.1]
  2   244    0   1.00  1337.00    8.85  10.13.215.122 [10.13.215.122]
  3   244    0  70.00  1366.00   86.11  172.26.96.161 [172.26.96.161]
  4   244    0  72.00  1316.00   86.07  172.16.126.124 [172.16.126.124]
  5   244    0  72.00  1282.00   88.45  12.249.2.49 [12.249.2.49]
  6   244    0  75.00  1242.00   90.10  12.83.180.82 [12.83.180.82]
  7   244    0  73.00  1200.00   94.24  12.122.110.5 [12.122.110.5]
  8   244    0  76.00  1142.00   87.52  12.91.205.18 [12.91.205.18]
  9   244    0  77.00  1519.00  119.13  att.com [144.160.155.43]
No packet loss, average ~120 ping time. Nice!
And here are the results from my desktop with a fresh install of Win 10
Target Name: att.com
         IP: 144.160.36.42
  Date/Time: 12/5/2020 1:20:08 PM - 12/5/2020 1:30:08 PM
Hop  Sent  PL%     Min     Max     Avg  Host Name / [IP]
  1   244   87    1.14    2.18    1.70  attwirelessinternet.wirelessi
 nternet [192.168.1.1]
  2   244   87    1.97    4.53    2.86  10.13.215.122 [10.13.215.122]
  3   244   87   71.82  128.56   86.11  172.26.96.161 [172.26.96.161]
  4   244   86   72.58  112.16   81.20  172.16.126.124 [172.16.126.124]
  5   244   85   75.31  135.54   86.50  12.249.2.49 [12.249.2.49]
  6   244   85  120.48  158.56  131.24  12.83.180.82 [12.83.180.82]
  7   244   86  121.15  156.61  131.42  cgcil21crs.ip.att.net [12.122.1.173]
  8   244   86  120.26  239.00  138.90  12.123.159.17 [12.123.159.17]
  9   244   86  127.61  152.23  133.73  12.249.81.194 [12.249.81.194]
 10   244   89  132.69  151.72  139.47  att.com [144.160.36.42]
Basically 90% packet loss.  
  Also ignore the time stamp on the laptop one, I didn't set the time on it, these where run at the exact same time, both on the same wifi.  Also it makes 0 difference if I plug into ethernet instead of wifi.
I suppose I'm going to start looking for a christmas deal on a new MB, CPU and RAM.  MSI says this MB is fine with Win 10, but something in my system is obviously not happy with it.