Thanks for responding guys. Zyndo, I felt my test setup for both the cards was pretty similar (I could be wrong though). I am using the Asus Gpu Tweak 2 software and when I switch one card out for the other, the software just recognizes it as a another strix 1080 and all my settings (just the fan control actually) apply to the replaced card. The fans speed seems to be in accordance with the fan profile I am using (for both cards). For the cooler card at load, T = 63C & fan speed = 2800rpm, where as for the card running hotter, T = 75C & fan speed = 3300rpm.
I would check if the thermal paste is applied correctly, but that would mean removing the sticker on one of the screws. So as DrMikeNZ suggested, that would be my last option. I know this doesn't really count but I did check the contact of the chip to the heat pipe from the side (using a flashlight and without taking anything apart), the application of the thermal paste seemed pretty similar.
I feel (just a theory, looking forward to what you guys think) that Asus is actually testing the chips and trying to overclock them. The ones that don't overlock well are assigned the "ROG STRIX-GTX-1080-8G-GAMING", the ones which belong to the silicon lottery get the "ROG STRIX-GTX-1080-O8G-GAMING strix" badge, and I just found out that there is another version "ROG STRIX-GTX-1080-A8G-GAMING" . So based on this information I don't think the buyer has the option to buy the base model (Non-OC) and then OC it on his/her own. This is because Asus would have already tested it out and assigned it to the lower category of cards. Since it still out performs the founder edition, they still are within their rights to sell it as a "strix" model (As DrMikeNZ suggested).
Anyway, I will keep you guys informed about how thing pan out.