Umm...
I had to do some Googling to find anything that said anything at all about what the i7-875K *sol
d* for, when it
was being sold.
$342~ and that was all the way back in early 2010.
The i7-875K is an extremely old and very out of date processor, especially for the money.
If you are thinking about upgrading to this, then that means you have the money for an i5-3570K + ASRock Z77 Extreme4, which would be a much better deal to upgrade to.... not to mention can easily be overclocked to 4.3-4.5GHz.
As seen here, the i5-2500K is beating the i7-870, and it seems that the i7-870 was for some reason, slightly better than the i7-875K, going against Intel's typical numbering patterns, but alas, it was a more expensive CPU.
Frankly, an i5-3570K will do *even better* clock for clock as opposed to the i5-2500K and is a newer and stronger tech.