For anyone new coming to this thread, I have yet to get my 970M to work properly in my M17x R4 running Windows 7 64-bit, but these are all the steps I have tried so far.
1. Downloaded and successfully installed Eurocom modded driver version: M17xR4_05511028_9xxM_399.07_W7_W8.zip [Alienware (Dell), GPU, Nvidia driver version, supported OS]. MSI Afterburner showed GPU1 (970M) activity, meaning the driver worked correctly. However, I still felt I was lagging in games unnecessarily considering I have 22GB of RAM. Therefore, I wanted updated modded drivers because I thought that might fix the issue given that these drivers were more than 2 years old.
3. Downloaded newest default 970M driver version from Nvidia website (417.35).
4. Edited nvdmi.inf file so driver would work on M17x R4 as per this guide.
5. Successfully ran setup.exe and downloaded the updated modded drivers. However, although recognised in BIOS and Device Manager as installed correctly, MSI Afterburner showed no GPU1 activity and I lagged worse in games. Therefore, I thought I might need to have an updated and/or unlocked BIOS set to start using PEG (PCI Express Graphics [970M]) for it to work.
6. Downloaded most recent default M17x R4 BIOS (A14) from Dell website.
7. Ran BIOS setup file and successfully updated BIOS from default A12 to default A14. However, still no GPU1 activity.
8. Requested an unlocked A14 BIOS from @Klem (many thanks <3).
9. Formatted a USB drive to run FreeDOS using Rufus as per this guide.
10. Extracted the DOS version of FPT, prr tool, and unlocked BIOS files all kindly provided by @Klem into the USB drive as per @svl7's original post.
11. Restarted the laptop, booting from the USB drive using the boot menu accessed by pressing F12.
12. Ran Flash.bat successfully and restarted again.
13. Opened successfully modded BIOS and selected 'Load (or restore) optimal defaults' under final 'Exit' tab, before pressing F10 then enter to save and exit.
14. Same as initial situation - outdated modded Eurocom drivers showed GPU1 activity and modded newest drivers showed no GPU1 activity.
15. Restarted and opened BIOS and went into new second Advanced tab, and changed Primary Display to PEG and saved and exited.
16. Laptop failed to start and it beeped several times with the fans running loudly.
Up until two days ago, I had no idea about driver modding or BIOS unlocking or how to do any of this, but I feel I have pretty much comprehensively tried everything I have been able to find to no avail. I am very tired as its 4am and am truly at a loss as to what to do. I've seen people have managed to fix their laptops by booting into the old AO5 BIOS or something, so I will be doing that shortly, but after that I'm pretty lost.
Any help on this would be insanely appreciated. :/
EDIT: I'm going to sleep now, and would be super grateful if someone could quote the fix for the beeps problem that was posted earlier in this thread, because I really don't want to have to look through all 26 pages again because I just finished doing that :'(.