DescriptionMajor challenge in mobile gaming is to find a sweet spot between performance and power consumption. DVFS (Dynamic Voltage Frequency Scaling) is widely-used power management method. Samsung Exynos 2100 introduces AMIGO (Advanced Multi-IP GOvernor), a DVFS governor to balance performance and power consumption in game-playing scenarios. Monitoring hardware must be turned on during game playing. Thus, it consumes constant power under constrained power budget. We propose an approximate Workload Watcher (WOW) for low power consumption in game playing. WOW measures three key metrics to identify workload characteristics in a given period. For IP-level approximation, we devise simple latency measurement strategy, because latency measurement requires large memory structures to track all transaction types. We measure read latency referring to first data, without last data. Because request to first data latency mainly contributes to read latency. For system-level approximation, we assume that traffics from IPs are evenly distributed to each DRAM with interleaving/hashing logic so that bandwidth measurement for one channel should be the same for other channels. Therefore, we can monitor with single partially turn off, for saving power consumption. WOW achieved 72% of power savings and 85% area reduction with proposed optimization efforts, compared to conventional debugging purpose IP.