Right I have looked at your post from the link above.
First of all as said all of the voltages for the 3.3v 5.0v and 12v rails reported are fine.
You are always going to get a slight fluctuation in voltages. Yours are less than 5%
Your beeping is not, or may not be related to the graphics card at all.
Instead it may be an indicator that the Cpu is reaching a thermal shutdown temperature.
A board will indicate this by a steady set of beeps or pulses.
So check the temp of the cpu. Make a note of it when the beeping starts.
Restart the system and enter the bios of the motherboard and check what the thermal shut down is set to and set it higher.
The other thing linked to that is what we call the fan rotation speed rpm.
If the fan spins to slow at one point the board will also beep in pulses thinking the fan has stopped working as a warning. Low fan warning speed in rpm.
When Idle in the bios check to see what speed the fan is spinning at in rpm.
Then look at the lower trigger value.
If the fan is spinning lower than the set rate it is because the trigger is picking it up ans sounding an alarm thinking it has failed.
Set it lower or turn the option of to monitor it in the bios.
Again this the fan or rpm speed can be set in the bios manually or the board can manage it.
This is why you are getting a steady beeping, or pulsed beeping of a single short beep.
My board does this and most new ones do.
If my fan drops below 600 rpm it starts to complain by the same method as your system does.
So i turn off the low rpm trigger in the bios or lower it.