The update is feasible.
The update is feasible.
One long and three short indicates a GPU issue. Without a dedicated GPU, this might also apply to iGPU problems, or it could stem from a beta BIOS. If the iGPU is struggling, the problem likely lies with the beta BIOS itself. VGA works analog while HDMI is digital; you require an active adapter to translate signals between them, typically directional—either from HDMI to VGA output or vice versa. A faulty adapter or mismatched setup could be the cause.
For X99 specifically the Deluxe II model, the AMI beep code missing in the manual can be found in the Trouble Shooting part of this forum unless it's detailed in your owner's guide. One long beep followed by three short ones indicates a memory issue above 64KB, though it doesn't seem to affect performance. I've heard the long beep after the error means all self-tests passed, but the video was then cut off. The 5600G is only compatible with revisions 2409 and later.