2600k with a lame core/thread?

[kandor]

Hi,

I have an older 2600k that I ran overclocked (but not hot) for 3 years approx. 4.7 ghz on a p65 sabertooth. At one point a few months back it began to blue screen occasionally in a certain rendering application. So, I reverted to stock clocks.

The weird thing is is that out of the 8 threads, one thread, even though it pegs 100% still, lags significantly from the other threads when rendering. It's totally noticeable when monitoring the render progress.

Is this a thing that can happen when a proc gets old? Damaged in some way? Is there a way to test empirically?

Thanks,

 

[rabidz7]

Just turn off the core in UEFI and use the CPU as a tricore not a quadcore.

 

[munkle]

Four of the 8 threads aren't really full performance threads. Basically the cpu interweaves instructions so that the core is more efficiently utilized. So if you are maxing 4 cores, there may be places for the cpu to interweave those extra 4 threads or there may not be. This is why you don't see double the performance from an i5 (4 threads) to i7 (8 threads). Could be that is what you are seeing here, there are times when turning off hyperthreading can improve performance and that may be what you want to try.

Just turn off the core in UEFI and use the CPU as a tricore not a quadcore.

Probably not the issue here at all. If the core were defective he'd probably still be running into bsods and 2 threads would be giving issues. I would say turn of hyper threading and see if all threads are the same speed.

 

[wabbitseason]

I'd tend to agree with munkle. If you had a defective core you'd have 2 lagging threads, not 1.

If you're still getting performance improvements in rendering over HT-off, keep HT-on. Otherwise, turn it off. Not much else can be done here, besides a complete reinstall of your OS and a fresh BIOS on your motherboard.

 

[unclewebb]

When a CPU is fully loaded with an app, there are still Windows background tasks that need to be constantly processed. If the background activity keeps getting scheduled on the same thread or the same core, over time it will look like this thread or core is lagging. All active cores in a Core i CPU run at the exact same multiplier so each is pulling its own weight equally.

Processors do get old and the overclock can slip a little over time but in your example, that's not what is causing the lagging core.