Dell never validated/tested Windows 7 on the Vostro 15 5568 =

So finding Windows 7 drivers will be an issue for you. From what source are you trying to install Windows 7?

Hi Chris, I'm having the same problem to install win7 on my vostro 15 5568, I'm tryng to install it from usb flash drive, what can I do to solve that problem? thanks

Hi Yosialash,

As per Chris, since this system was not tested with Windows 7 and there are no drivers available directly, it is not recommended to attempt an install of Windows 7. I haven't personally tried Windows 10 drivers w/ Windows 7 and while I know they might/can work it will sometimes be tricky.

With that said, if you're still looking to install 7 you will want to use a USB key and use something like this.  Here is a link where a customer got it working on another system that was shipped with Windows 10. 

Please note, that this is not something that we (Dell Support etc) can offer support for, but you're definitely welcomed to try this. If the above Intel link does not work for you, this is basically what you would need to do to get 7 to install (somehow get the chipset/usb 3.0 to be recognized prior to install). I hope this helps, and good luck with the install! I would also recommend imaging the original Dell drive/using a different drive for this in case this doesn't go as planned.

Best regards,

Brad