What possible reason could they have for this, apart from forcing users to buy their 'unlocked' chips? Is it really worth the nightmarish PR debacle they will undoubtedly face?
Side note (from comments) -- apparently Intel paired this microcode update with a patch to fix CPUs freezing during Prime95. Not cool.
Nightmarish PR was probably an overstatement, but I would expect a considerable backlash from customers who will be having a free feature removed-- for no reason other than to make Intel money.
Seeing as AMD are getting back into the game with their new Zen architecture, I think this is a very unwise move by Intel.
Very true, but having the loophole there is beneficial for users who want to overclock it-- bug/feature debate aside.
They advertised it as non-overclockable, but some users found out it was -- why bother patching? To force those users to buy the more expensive 'unlocked' chips for something that used to be free.
The irony is that if you are running Prime95 and overclocking, Intel should love you, because you are going to be in the market for a new processor much sooner than the average user.
Prime95 slowly cooked several PCs that I had the pleasure of supporting through my years in college.
I love what Prime95 wants to do, but consumer PCs are not usually designed/maintained with 100% CPU usage in mind.
Even more you can probably compare these users to the "sneaker heads" that keep the Nike brand going by waiting in line for underpriced limited edition sneakers.
The unfortunate difference probably boils down to sneakerheads being a substantial portion of Nike's high-end business, while overclockers and computer performance enthusiasts are nothing more than a rounding error in Intel's balance sheet when you compare them to a customer like Amazon buying chips by the thousand. It doesn't matter if your average overclocker buys a new chip every year to keep up with the latest and greatest instead of every 4 years like his less-savvy friends might.
Overclocked CPUs run hotter. For modern technologies that means they can degrade faster, and can fail earlier than their expected lifetime. To be clear, I'm not saying this is the reason Intel did this, but it is one possible reason, and you asked for possible reasons.
CPU's don't really break in any timespan that matters to the consumer, be that with or without overclocking. How many times have you had a CPU break? I know of no one who has broken their modern CPU due to overclocking or otherwise.
I have had one break. It was flooded when a pipe burst in the house near the computer. And the whole CPU didn't break, only part of the memory controller. So for a while I ran an A10-5800K in single channel mode with a single stick of RAM until I could buy a new CPU. Interestingly, I had water pour out of my HD-7950 (it was completely submerged), and it is still running fine a couple of years later (I did dry it for days on a fan, then completely dissasemble it, wash with isopropanol, and re-assemble it very carefully).
They are much hardier than we give them credit for.
I have seen CPUs bricked from moderate air-cooled overclocking. And it is still possible to kill a chip by feeding it the wrong voltages as long as the motherboard allows it.
Admittedly I don't know how far we are down this line, but as transistors are getting smaller, and the number of transistors in a processor is increasing, transistor degradation during the processor lifetime is becoming a larger issue, and Skylake is already at 14 nm. I think even experts in the field will be unable to give statistics about Intel processor durability, as Intel are not very forthcoming with such statistics.
> Overclocked CPUs will only run hotter if voltage is increased beyond default
Raising either voltage or frequency increases power dissipated. P = C V^2 f, where C is a constant that depends on the physical structure of the gate, V is the voltage, and f is the frequency that the gate's logic state is changing.
Side note (from comments) -- apparently Intel paired this microcode update with a patch to fix CPUs freezing during Prime95. Not cool.