Switch i5-3360M with i7-3520M - is full OS recompile needed?

[an7h]

I've got a Thinkpad T430 and would like to upgrade the CPU. Considering these CPUs are in the same generation and pretty similar, is it really necessary to recompile WORLD and the kernel in order to achieve full stability and performance? I was wondering if spending time is really necessary in this case.

[eccerr0r]

Yes, since they are the same generation, I don't think you'd see much if any improvement at all if you tweaked compilation options... and even with the i7, just a few percent for the clock speed increase otherwise nothing really noticeable.

[Hu]

Assuming that the new CPU is at least as capable as the old one in terms of supported instructions, then there is no need to recompile at all. You might get improvements from rebuilding, but like eccerr0r says, I doubt it would be worth your time. If it were me, I would not explicitly rebuild anything, and instead rely on the incremental rebuilds from general updates to migrate the system over time.

If the new CPU is not able to run some instructions that the old CPU can, and you built your programs to use those instructions, then you could get in trouble. Check Ark to see whether the old CPU has any features that the new CPU lacks. If it does, then you might (or might not) be configured in a way that will have trouble. If it does not, then you cannot have any programs that will start failing when the CPU is changed.

[an7h]

@eccerr0r
@Hu
Thank you. yes, I suspected as much. These two CPUs are almost identical, which is why I thought that maybe there is no reason to recompile everything? The i7 just has higher clock speeds and more cache. It's not really much of an upgrade compared to the previous CPU, but it's cheap the get one, so why not?