What is the type and specks of your PC - windows ? if so what version ?
Are you intention to use this PC only for navigation
?? or multi use ??
Your problem seems at first look to be a poor /& vrong vga driver but difficult to know for sure.
Would recommend to try to download the latest Opencpn
for your operating system from Download OpenCPN | Official OpenCPN Homepage
and try to start opencpn
after installing. If windows, go to system-> decivemanager with your GPS
plugged in. Look for crratd COM port and note the higest number, normally COM3. Go to opencpn menu/settings and choose connections. Add a new connection and chose serial
. and mostly you will see your GPS as COM3. press apply and check "show NMEA
debug Window. Do you see the NMEA
stream with green letters in that window ?? Then everything is just fine. The latest opencpn has chart downloader included in the install so you can download all official nooah charts
using the chart downloader. Be sure to enable the chart downloader in the plugins menu before going to charts->chart downloader.