Glad you got it.  Didn't know a chipset driver was needed to install Win7 in a 7040.  I moved an HDD from a 755 to a 790 some years ago.  It was functional, just needed chipset, graphics, and sound drivers. Sometimes I still learn too.  Did you install chipset driver with Win10?
Hi i wanted to install windows 7 on my optiplex 7040, but i dont have the drivers to install it on my computer. And if i try to use different iso that already has usb 3.0 Support then it bluescreens. Well i need to know actual link to get the windows 7 usb 3.0 driver.   My optiplex 7040 specs: Processor: Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz SSD [MAIN]: Patriot P210 512GB HDD [SECOND]:  ST3000VX010-2E3166 GPU: NVIDIA GeForce GTX 1050 Ti RAM: 16 GB    
How do i install Windows 7 on my Optiplex 7040?