From what I understand, chip manufacturers design their processors to operate in a certain frequency range, and they are tested to be stable within these limits. If this limit is exceeded, the dependability of the chip will be compromised. Even if certain individual chips on the production line can run faster than the next one coming down the conveyor belt, the company has no (easy) way of indicating those specific chips, so they rate the whole family at the lowest common denominator - the highest speed at which
every member of that processor family can reliably run. Hence you get some chips that can run at the manufacturer-rated maximum speed, and others that - due to manufacturing process differences - can run significantly higher. This may explain the issue with our phones; you have some Snapdragons that can run reliably at the maximum speed our tweaked kernel allows, and others which only perform to the manufacturer's specifications. I've researched the Qualcomm documentation on our chips, and they are rated at a maximum of 1.4GHz. I wonder if even the people who have trouble running an OC kernel could run at this company-specified maximum speed... a good way to check would be to use Shin's 1.7GHz kernel (which defaults to the stock 1GHz by default, but has the ability to achieve higher speeds after being told to do so by a CPU control app) at the stock speed, and see if it boots and runs as intended. If so, then bump the speed up a notch and try again. This could be repeated until the maximum stable speed is found for your specific phone. I would try this myself, but my phone is happy at all clock speed values that I've thrown at it.
Who knows? Maybe those certain "over-achieving" chips could be pushed to even further than 1.7 if the kernel allowed it