Localized heating-up creates thermal hotspots across the chip, with the integer register file ranked as the hottest unit in high-performance microprocessors. In this paper, we perform a detailed study on the thermal behavior of a low-power value-aware register file (VARF) that is subjected to internal fine-grain hotspots. To further optimize its thermal behavior, we propose and evaluate three thermal-aware control schemes, thermal sensor (TS), access counter (AC), and register-id (ID) based, to balance the access activity and thus the temperature across different partitions in the VARF. The simulation results using SPEC CINT2000 benchmarks show that the register-id controlled VARF (ID-VARF) scheme achieves optimized thermal behavior at minimum cost as compared to the other schemes. We further evaluate the performance impact of the thermal-aware VARF design with the dynamic thermal management (DTM). The experimental results show that the ID-VARF can improve the performance by 26.1% and 7.2% over the conventional register file and the original VARF design, respectively.