Soldato
I'm pretty sure the problem is with the DVI-VGA adapter.
Not that it is broken, but it is the wrong type for the job. Most likely it is an adapter than converts from DVI-I (or possibly DVI-A) - which has a proper analogue signal within it - to VGA/D-Sub which is also analogue.
Instead, the OP is trying to use it to convert a VGA output (analogue) to work with the purely digital DVI-D port on the monitor - which will not work as these adapters just swap around the pins, and don't do any analogue to digital conversion.
If the OP bought a proper VGA to DVI-D converter which does this active conversion - then it should work (i'm not sure about the "default 120Hz" thing), but it would certainly work in the standard HDMI port (which is 60Hz). However, these devices are not cheap - and IMHO the money would be better spent either buying a new monitor with a native VGA input (and selling the very expensive 120Hz monitor if it is no longer needed) or importing a HIS PCI HD 5450 graphics card from the US.
Not that it is broken, but it is the wrong type for the job. Most likely it is an adapter than converts from DVI-I (or possibly DVI-A) - which has a proper analogue signal within it - to VGA/D-Sub which is also analogue.
Instead, the OP is trying to use it to convert a VGA output (analogue) to work with the purely digital DVI-D port on the monitor - which will not work as these adapters just swap around the pins, and don't do any analogue to digital conversion.
If the OP bought a proper VGA to DVI-D converter which does this active conversion - then it should work (i'm not sure about the "default 120Hz" thing), but it would certainly work in the standard HDMI port (which is 60Hz). However, these devices are not cheap - and IMHO the money would be better spent either buying a new monitor with a native VGA input (and selling the very expensive 120Hz monitor if it is no longer needed) or importing a HIS PCI HD 5450 graphics card from the US.