It says bios switch. So it switches between different bios options.

Right below your arrow, it says Bios Switch.

To the left of your circle are 3 led's labeled Bios 1, Bios 2, and Bios 3. The 3 led's are typically 3 different colors. Example would be bios one is a white led, Bios two is an amber led, and bios three is red. You would need to move the selector to see the options to know the difference.

When you move the selector, you move to a different bios.

You can load multiple different bios on multiple different chips, so that you can find one that works and test overclocks on a different bios. Then, if an overclock goes bad, you can move the switch, and reboot, switch to a different bios and reflash to restore original settings.

Hi the_Scarlet_one
 
Thanks for the answer. But I have new questions.

I've already installed the operating system - Windows 10, unfortunately. And I don't know what position I have in the switch BIOS selector. Windows 10 works sustainably. I'm afraid if I switch this selector and load another BIOS, Windows 10 will be shattered.

1. Can I switch the selector and not load the operating system by pressing F2?

2. Can I switch the selector and load another operating system, such as Linux?
 
Regards

To clarify Saijin's answer, you can flip the switch and then enter BIOS, and you can load a different operating system, but unless you set a different hard drive as the default you won't be able to change OS just by choosing a different BIOS location. 

bcavnaugh
Maybe you could if you set the First Boot Device in each Bios for each OS?

That is what I am thinking. Would be a great idea honestly.

Hello, guys.

Thank you very much bcavnaugh, the_Scarlet_one, EVGAtech_BrandonS. This is my dream: switch the BIOS and it will set another First Boot Device. And I can download another operating system from a different boot device now! It is my dream. What are the problems here?

1. I will need to get under my desk every time if I want to work with another operating system.
2. I will need to open the system unit lid every time to access the BIOS switch.
3. I will need to switch the BIOS selector to the desired location each time.
4. I will need to close back this lid every time.

What is the alternative?

I can try to install another operating system (Linux) using the four existing UEFI partitions. I already tried that. Linux is very poorly installing on these four partitions. It's trying to pull to the system and set up his very heavy and bulky loader GRUB-2. They say I can discard the bulky GRUB-2 and add another boot record to the EFI system partition (with FAT32) for another operating system. But I don't know how to do that?

Guys, help me please. What would you have done?

Thanks for all of everyone's help.
 
Regards

You could give Mobile Rack Drawers a try.
Make Sure though "Maximize performance, with file transfer speeds up to 6Gbps when paired with SATA III"
I like this one. (3.5" Drives)
StarTech.com 5.25in Trayless Hot Swap Mobile Rack for 3.5in Hard Drive - Internal SATA Backplane Enclosure
 
This one for SSD Drives: (2.5" Drives) Down Side Supports TWO 2.5" SATA I or II Hard Drives or SSD
Vantec NexStar SE Dual 2.5-Inch SATA Hard Drive Rack MRK-525ST (Black)
 
I bet you can find some that are SATA III 6Gbps one somewhere.

Tytanxamon
Guys, help me please. What would you have done?

I would just use the BIOS boot selection to choose which drive to boot (on EVGA boards I think it's the ESC key). So connect Windows drive to system, install Windows, disconnect Windows drive; connect Linux drive, install Linux; connect both drives, set which one you want to be default in BIOS. When you want to switch just hit ESC when BIOS screen is up, choose alternate drive from boot menu. No bootloader tricks or switch flipping required.

Keep a list or better pictures of all BIOS setting.
 
When it is BIOS update time you will not be able to load back BIOS setting parameter files.
 
( like many problem in life this one could be solved with a cricket bat )

we need a external bios switch