What does a locked CPU actually mean?

[TrivisionZero]

I mean, really?

Why is it impossible to overclock when you have a locked processor? Surely there is some hardware hacker out there that has figured out how to unlock a locked CPU. Or is it much more complicated? I really have no idea, as I'm new to everything here, so an explanation would be helpful.

Thanks!

 

[Justin Millard]

Simplest terms, locked means you can not overclock the processor.

I wouldn't worry about trying to overclock a locked processor, the performance gains would be minimal for a lot of effort.

 

[TrivisionZero]

But I'm asking, how? How do they lock the processors?

 

[Justin Millard]

They just don't let you easily change the voltages and clock speeds. Locked chips are usually binned from batches that were not expected to get the same performance as unlocked chips, so they lock them and limit their performance so nobody complains that the CPU is slower than advertised or can not overclock and asks for a refund.

 

[PsyKhiqZero]

No one really knows how they lock them. I assume a resistor inside the cpu or something that would tell the motherboard what the multiplier is and whether or not it could be overlocked. But that would be my best guess. But it is done inside the CPU. To date I haven't heard of anyone "unlocking" a locked intel cpu mulitplier.

 

[Justin Millard]

Yeah its done during the factory process.

 

[bmacsys]

You certainly can overclocked a chip with a "locked" multiplier. You just use the mobos reference clock. Having an unlocked multiplier is certainly easier. I have loads of Phenom II's that are locked and clock from 2.8 GHz to 3.2 GHz and I have them all running at the least 4.0 GHz. I am not as familiar with Intel chips and if its possible. Knowing them they make it very hard to do.

 

[Justin Millard]

Yeah intel definitely make it harder than AMD.

 

[Supernova1138]

You used to be able to overclock locked Intel chips, but that ended in 2011 with Sandy Bridge and the design changes it brought. Prior to Sandy Bridge you could overclock with a locked multiplier by changing the FSB/BCLK settings, it wasn't as easy to do compared to just changing the multiplier as you had to have RAM that could deal with the increased bus speed and you may have to mess around with voltages on the memory controller as a result, but it was possible. With Sandy Bridge onwards, you can't make any significant increases to the BCLK anymore, as it will cause instability due to just about every motherboard device being tied to it. I think the maximum BCLK increase you can do on Sandy Bridge or newer is something like 4MHz which translates into an absolutely tiny bump for the CPU clock speed. As such, for Intel you pretty much have to have an unlocked multiplier in order to do any significant overclock their chips now, some boards do allow you to bump up locked chips by about 200 to 300MHz by messing around with the Turbo Boost settings, but that's about it.

 

[synphul]

Locked cpu chips from intel are physically locked from the factory. There's no hack or voodoo to get around it, you either have a locked (non k) or unlocked (k) chip. You can still raise the baseclock on a locked cpu but baseclock (bclk) affects more than just the cpu. It also overclocks the memory, the pcie slots etc. If you're lucky you might get the baseclock from 100mhz (default) to 110mhz or so. So if you have an i5 4460, it has a max turbo of 3.4ghz (x34 multiplier). 34 x 110 = 3.7ghz. At best you'll get about 100-200mhz increase and 110mhz would be a 'good' baseclock jump. It may handle less, a small rise in baseclock causes quick system instability and it's not a good idea to go pushing all the subsystems up.

That's the reason for leaving the baseclock alone and raising the multiplier which only affects the cpu (and uncore which affects the memory controller independently) on a k series cpu with a z series motherboard. There's a reason they lock certain components at the factory, it didn't pass specs to be a better chip.

For instance I had an older nvidia card, I can't recall but I think it was a 6800gt and the 'hack' back then was unlocking shader units that had been factory disabled. Shortly after I did (maybe a week) the card was toast and had severe artifacting. Apparently they weren't up to the task which is why they came disabled. Bottom line, if you want to overclock, get a k series and an appropriate motherboard.