USB - I used a 32gb Transend USB 3.0 thumbdrive, my older usb's didnt work
So for anyone seeking to find "the USB stick" to use for firmware updates, please read this first, because this is really odd...
Back in August, I recieved an N6 S/N G9. I tried it with my 32GB Sandisk Ultra USB 3.0 thumbdrive and no matter how I formatted it as FAT32 (i.e. using differing block sizes, bootable vs non-bootable etc), the N6 G9 would not detect the firmware image file that I placed on it. So I read around on the internet and found that people were saying that the thumdrive needed to be 4GB or less and USB 2.0, not USB 3.0 in order for it to work. So I ordered a random 4GB USB 2.0 thumbdrive (a Gigastone 4GB). Formatted it as FAT32 (non-bootable, but don't remember the block size that I used), copied on the 1005.4 firmware image (the latest image at the time), plugged it in to the service port of the monitor and it worked fantastically, the monitor detected the firmware and I was able to update. Great.
Role on a few months, after sending back the N6, N8 and now the N9 models that I had received (because they all had different problems), I have now received an NA model. "This one seems like the one!" I excitedly thought to myself as I tested it out and found that it didn't have the issues that my prior G9 attempts had. I had noticed that it has a little more backlight bleed than I'd like, but it's not bad - I'm probably being pedantic to be honest. The only thing is, it was flickering like crazy in certain scenes, but I'd read that firmware 1008.1 in conjunction with the latest Nvidia driver should hopefully fix that, so I reached for the 4GB Gigastone thumbdrive, deleted the 1005.4 firmware image (that was still on there since updating the N6)..... and copied on the 1008.1 firmware image, plugged it in the service port and nothing, the NA S/N model couldn't detect the firmware. "Uh oh, that's not good" I thought to myself. I then tried reformatting the drive as FAT32 multiple ways (e.g. trying different block sizes) and then copying the firmware onto it, but no matter what I did, the NA S/N monitor would not detect the 1008.1 firmware image. At this point I was starting to feel depressed, I'd finally recieved a G9 that was looking great, but it wouldn't update! In desparation, I grabbed the 32GB Sandisk Ultra USB 3.0 thumbdrive that wouldn't work with the N6 S/N model (no matter what I did), deleted the 1005.4 firmware that was still sitting on it, simply copied on the 1008.1 firmware image, plugged it into the service port, and much to my surprise and delight, the monitor detected the firmware and updated. I then installed the latest Nvidia driver (460.79) and the flickering issues had disappeared!
So, in short, the thumdrive that worked on the N6 G9, didn't work on the NA G9. Conversely, the thumbdrive that worked on the NA G9 wouldn't work on the N6 G9. So I'm guessing that either the hardware has changed between the N6 and NA G9, or more likely, the sticks that work, depend on the revision of the firmware you are using, which if true, is crazy.