clock skew is used to help fix clocktimings that are out of whack due to overclocking. Sometimes helps to delay CPU skew a bump or to to get stability at bleeding edge clocks.
IOH Core and ICH I/O Core really help when running 3D benchmarks. Many say it helps with crossfire/SLI, I found it to be really helpful pushing my 4890 past 1000 MHz Core IOH core also helps with high overclocks (chipset voltage)
ICH I/O not really sure what it is, but it helps boosting it. Mine is called IOH ICH I/O vcore. Technically ICH is 'I/O controller hub'. So probably something to do with QPI.
ICH core is southbridge on my board, I usually bump it up a bit but not too much 1.175 to 1.2 again the acronym does not fit the purpose, but if you have been delving into BIOS for any period of time, its really obvious that most mobo manufacturers have their own ideas on what to call stuff
Google can help you with clock drive, apparently lowering the settings can help stability. Judging from what I read it smells reminiscent of GTL REF
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Hybrid Mode
