Updated: 28th Dec 2019

Rarely, Windows might need a clean install. We’ve uploaded a few steps on how you could clean install Windows. This guide is specific to the Dell laptops. 

Part 1: Download what you’ll need.

Step A: Use Microsoft's free Windows 10 Installation Media tool, to create a Windows 10 boot USB (the USB has to be at least 8GB in size). 

https://www.microsoft.com/en-gb/software-download/windows10

Step B: Once the USB has been created using the tool, make a new folder (Call it “Dell Drivers” to be simple, you can use other names, as long as it does not clash with any folder name what's already there; this folder intends to hold the optional drivers for you to install later).

Step C: Download “Dell Support Assistant” into the new folder (this tool helps the laptop to automatically find many Dell drivers - once you've installed Windows - it's really helpful): https://www.dell.com/support/contents/uk/en/ukbsdt1/article/product-support/self-support-knowledgebase/software-and-downloads/supportassist

Step D: Download the graphics driver into the folder where applicable. Skip this step if your laptop does not have a dedicated graphics card. For NVIDIA graphics card, goto NVIDIA's website & download the graphics driver (select the graphics card model; e.g. on Dell M6800 it would be: Quadro > Quadro Series (Notebooks) > Quadro K4100M.

(Direct link: https://www.nvidia.co.uk/Download/index.aspx?lang=en-uk)

Part 2: Backup all your data. 

Clean installing Windows 10, will wipe all your data - so make sure the data you’ll need is backed-up fully externally.

Part 3: Check AC Charger, Soft Power Reset, Reset BIOS to default

Step A: Plug the charger into the laptop, then check that the AC power wattage is detected correctly in the BIOS (goto Settings > General > Battery info); if it doesn't state a wattage - get in contact (or perform 3B+3C & check again, additionally, try to use a different plug socket).

Step B: Remove the AC Charger from the laptop & where applicable, also remove the battery. Now, press down the power button for 30 seconds. Then connect the AC charger in (without the battery).

Step C: Important - load the default BIOS setting (Press F2 again immediately after the boot-up, select "Load Defaults" - Yes to applying. Then Click on "Exit". Once the computer reboots, the Dell logo should appear. After 20 seconds, switch off the system. Reinsert the battery back in. This sometimes improves the stability of the systems. 

Part 4: Normal Legacy install (this applies to most laptops)

Models to apply this to: Dell Precision M4600-M4800 & M6660-M6800 (and most other laptops).

If you've completed Part 4A, then simply skip part 4B & go to part 5 (this is the case for most laptops); if you have a model highlighted in 4B - complete step 4B, then skip 4A & goto part 5 directly.

Step A: Switch on the laptop, update these settings, in BIOS (press F2) goto:

1. Settings> Secure Boot > Secure Boot Enable: ensure that the "Disabled" option is ticked.

2. Settings> General> Boot Sequence: ensure that the "Legacy" option is ticked.

3. Settings> General> Boot Sequence: ensure that the first/top drive selected is what you want to use as the boot drive on every boot (this is usually Internal HDD /or a disk with your SSD’s name on it). 

4. Settings> General> Advanced Boot Options: ensure that the "Enable Legacy Option ROMs" option is ticked

5. Settings> System Configuration> SATA Operation: ensure that the "AHCI" option is ticked

If an option is already ticked as mentioned above, then move to the next step (ideally in that order). However, if any option requires changing, then after you have ticked the option, press “Apply”, then “Exit”; once the computer reboots, the Dell logo will then appear. Now immediately press F2; check that the previous option has been saved, and move to the next option update. Once you’re done, goto step 5 (skip 4B).

Part 4B: UEFI Windows install* 

*Try to use Part 4A (Legacy boot) instead of 4B (UEFI boot) where possible. Part 4B could be a substitute (to 4A) where if no SSD/HDD has been detected during Windows install with 4A. However, UEFI install is harder to set up correctly - as a result the Legacy boot mode could be more robust to use).

Models to apply UEFI boot to: Dell Latitude 7490 / XPS 9350 / 9550 or newer.

Step A: Set these settings, in BIOS (press F2) goto:

1. Settings> General> Boot Sequence: ensure that the "UEFI" option is ticked.

2. Settings> General> Advanced Boot Options: ensure that the "Enable Legacy Option ROMs" option is unticked

3. Settings> Secure Boot > Secure Boot Enable: ensure that the "Enabled" option is ticked.

4. Settings> System Configuration> SATA Operation: ensure that the "AHCI" option is ticked (this is because sometimes UEFI+RAID causes compatibility issues)

If an option is already ticked as mentioned above, then move to the next step (ideally in that order). However, if any option requires changing, then after you have ticked the option, press “Apply”, then “Exit”; once the computer reboots, the Dell logo will then appear. Now immediately press F2; check that the previous option has been saved, and move to the next option update. Once you’re done, go to step 5 (skip 4A).

Part 5: Install Windows.

Insert the Windows 10 USB you’ve made.
Press F12 immediately after boot up > One-off boot device > select the USB
Install Windows

Part 6: After Windows has been installed.

Step A: Once you're in Windows:

1. Install the graphics drivers first. Initially, the system will appear to be less responsive / the internet appears slow. This is because it is updating the drivers in the background. An idea is to leave the laptop for 10-15mins whilst it setup (depending on your internet speed this could take longer).
2. Then open "Windows update" - let it find more drivers (restart once it requests).
3. Then click on the Dell Support Assistant, use it to install the remaining updates automatically. Note: this app normally takes a while to install in the background. It doesn't always pick up all the drivers you might need. If it gets stuck during its opening, just restart the system and try loading this app again.
4. Missing a specific driver? Visit Dell's support site then either type in the model number (e.g. M6800), or the laptop's specific Service Tag (on the base cover usually/or visible in the Dell Support Assistant App). The latter has a narrower range of available drivers, though also that means selecting the incorrect driver is less likely (link: https://www.dell.com/support/home/uk/en/ukbsdt1)

Step B: If in doubt - read Dell's article on the correct order to install the drivers:

• https://www.dell.com/support/article/uk/en/ukbsdt1/sln148687/how-to-install-dell-drivers-in-the-correct-order?lang=en