Hi all! I have a PowerColor PCS+ HD7870 Myst. Edition 2GB - Tahiti Le but i cant change the VDDC. I tried with Trixx 4.4b, Asus GPU Tweak 188.8.131.52, PowerUp Tuner 0.2.1, MSI AB 2.3.0. The card uses a CHiL CHL 8225 for voltage control. It offers monitoring and software voltage-control features and is well supported through overclocking software. I found this review. They are using Trixx 4.6 but I can't find it. Pls, help me find out how can i change the voltage. Default boost voltage is 1,256V. My card running 1260/1725 @1,256V, but i want under voltage it, and find out how much voltage needed to 1100Mhz. And if you have a solution how can i disable the boost then pls tell me. I tried 7950 non boost bioses, but not working. Thanks!