Windows 10 update.

You won't be able to if the motherboard wasn't designed to support UEFI. Windows has supported UEFI since Windows Vista, but the hardware side didn't come online for most systems starting around 2012.

What is the exact make and model?

Open Start, type: system information
Hit Enter
Click System summary
Look in the right pane

Copy the system sku info into reply here.

See example: https://imgur.com/qzektpA

If your system is working fine, there is no immediate benefit in needing UEFI unless you are using a hard disk thats larger than 2 TBs and need security technologies like Secure Boot.

OS Name Microsoft Windows 10 Home
Version 10.0.17134 Build 17134
Other OS Description  Not Available
OS Manufacturer Microsoft Corporation
System Name DESKTOP-TRIRDJ4
System Manufacturer Gateway
System Model FX6860
System Type x64-based PC
System SKU 
Processor Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz, 3401 Mhz, 4 Core(s), 8 Logical Processor(s)
BIOS Version/Date American Megatrends Inc. P01-B2, 8/9/2011
SMBIOS Version 2.6
Embedded Controller Version 255.255
BIOS Mode Legacy
BaseBoard Manufacturer Gateway
BaseBoard Model Not Available
BaseBoard Name Base Board
Platform Role Workstation
Secure Boot State Unsupported
PCR7 Configuration Binding Not Possible
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume1
Locale United States
Hardware Abstraction Layer Version = "10.0.17134.1"
User Name DESKTOP-TRIRDJ4\gasdo
Time Zone Eastern Daylight Time
Installed Physical Memory (RAM) 8.00 GB
Total Physical Memory 7.98 GB
Available Physical Memory 3.84 GB
Total Virtual Memory 13.0 GB
Available Virtual Memory 3.82 GB
Page File Space 5.07 GB
Page File C:\pagefile.sys
Kernel DMA Protection Off
Virtualization-based security Not enabled
Device Encryption Support Reasons for failed automatic device encryption: TPM is not usable, PCR7 binding is not supported, Hardware Security Test Interface failed and device is not InstantGo, Un-allowed DMA capable bus/device(s) detected, TPM is not usable
Hyper-V - VM Monitor Mode Extensions Yes
Hyper-V - Second Level Address Translation Extensions Yes
Hyper-V - Virtualization Enabled in Firmware Yes
Hyper-V - Data Execution Protection Yes

Hi,

Win 8, 8.1 and 10 have a new feature called Fast Startup. It can sometimes cause problems like you mention as well as others.

The easiest way to tell if this is the problem is to turn it off and see what happens.

This feature only works when you do a SHUTDOWN and then Boot.

It doesn't effect a RESTART.

To turn it off or on...

Go to Control panel...Power Options, and select Choose What the Power Buttons Do on the left.

Then select Change Settings That Are Currently Unavailable near the top center of screen...

Lower down on the window, uncheck Fast Startup.

This may or may not help your problem, but is easy to check.

As stated, this system cannot be converted to UEFI.

Thank You, I was afraid of that. I just will not shut it down!