Voltage regulation of processor sub-domains supplied by a same voltage domain power supply rail. Voltage to certain logic units within the voltage domain may be reduced relative to other logic units of the voltage domain, reducing idle time at high power. In an embodiment, a first voltage-regulated sub-domain includes at least one execution unit (EU) while a second voltage-regulated sub-domain includes at least one texture sampler to provide flexibility in setting the graphics core power-performance point beyond modulating active EU count through power domain (gating) control. In embodiments, a sub-domain voltage is regulated by an on-chip DLDO for fast voltage switching. Clock frequency and sub-domain voltage may be switched faster than the voltage of the voltage domain supply rail, permitting a more finely grained power management that can be responsive to EU workload demand.