I wondered if my computer supports UEFI or not. I would like to install Windows 10 with UEFI configuration but my BIOS config doesn't have "Secure Boot" or "Disable Legacy Boot".
Press the WIN+R keys to open the Run prompt, type "MSInfo" and hit enter. Look for the "BIOS Mode" and it will shown as "UEFI" if your computer supports UEFI.
If you want to install Windows 10 with UEFI, you can use the freeware ISO2Disc to create a GPT bootable USB from Windows 10 ISO.
Vostro 3500 does not have UEFI or secure boot options. Also this model has not been tested with Windows 10, so not all features may work. Please refer to http://dell.to/2rgFB0b and http://dell.to/2rgrMig.
Please send me direct message by clicking on my username with the service tag and contact details. If the machine is out of warranty please contact Out of warranty support at http://dell.to/1TD76I0.