Motherboard is GIGABYTE 'GA-EP45-UD3P' REV 1.0
OS is Windows 7 / 64-BIT

This the information I could gather from the BIOS's Fan Speed
controls.

CPU Smart FAN control AUTO
CPU Fan Mode AUTO

SMART-FAN OPTIONS
AUTO -CPU SMART FAN is controlled by BIOS.
DISABLED --CPU FAN IS always running at highest SPEED!
ENABLED --CPU FAN SPEED IS NOT FIXED AND VARIED ACCORDING TO
CPU TEMPERATURE.

CPU FAN MODE Options
AUTO --no descriptions for setting
VOLTAGE --no descriptions for setting
PWM --no descriptions for setting

Which setting, for both options, are appropriate to be able to
increase or descrease the RPM of the Fan speed from within Windows?

My HSF FAN is average set to 1,500 RPM and it is of the most rare
circumstance that it goes beyond 1500. I want to be able to set it 500
RPM higher but be able to do it within GUI Windows.

So, which settings should I choose in the BIOS?
Then, what software, if any, do I need installed to be able to adjust
the FAN Speed?

Thanks for helping and reading my post..