With my E8600 @ 4.0GHz, VTT 1.275 bios (1.175 actual) I run (on Black Ops) -1, -8, -1 -8, dual core cpus will always be a negative value as opposed to the quad positive value.

The -1 is to account for the m/board anomally shown in saaya's "read" values for the E8600 as opposed to the m/boards "default" values

The -8 was arrived at using a combo of saaya's spreadsheet, the GTL calculator by Seban and LinX to graph results with regard to the optimal values.

For a 45nm dual core you need to achieve values as close as possible to .635 as opposed to a quad which utilises .667

LINK

NB GTL is still somewhat of a mystery to me at this stage