You have to fire up a powerful memory interface, drive requests back and forth over a high speed bus and actually pull the data from DRAM. Anytime you go off-chip for data the power penalty is tremendous. A larger cache means a higher likelihood of finding data in that cache, which saves trips to main memory. ![]() The other advantage is the larger 元 cache. Any energy expended from running at higher clock could be saved by spending more time at idle. Short bursts of instructions can execute up to 25% faster on the i7, allowing it to go back to sleep that much quicker. From the CPU's perspective, it wants to finish its work as quickly as possible so it can get back into its really low power idle states.įor workloads with balanced periods of load and idle time, the i7 should be able to at least equal the battery life of the i5. ![]() It's in these sleep states that it'll draw very little power and avoid being a major consumer of that 35Wh (or 50Wh in the 13) battery. The i7 needs tiny, tiny, tiny fractions of a second of idle time to throttle down and go to sleep. Where the i7 stands a chance however is in workloads where you aren't running the CPU at full tilt all of the time. ![]() Active power is greater at higher frequencies (assuming everything else remains the same) and with no chance to get to sleep the i7 will eat through the 35Wh battery faster than the i5. If you're running a high CPU workload that never lets up in a continuous loop, the i7 is going to die quicker than the i5. The 1.8GHz Core i7 doesn't run much faster by default than the 1.6GHz Core i5, but it can turbo up to a 25% higher clock speed than the Core i5.
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