Hello, I've just built a new system with an Asrock 970 Extreme4, AMD Phenom II X6 1090T, Sapphire Radeon 6950 and Cougar S550. I assembled the parts yesterday, but it does nothing, no spinning of the fans, no power on the drives, nothing. I am now totally desperate because I can not explain what it could be. It is not the first system that I've put together and I've been doing this since the i386DX. As far as I can tell, the assembly was working fine, everything is in the correct slots, everything is correctly connected. I checked whether: the CPU power supply with the 4-pin instead of 8-pin connector changes anything; if the 20-pin ATX power connector instead of the 24-pin changes anything (the MB instruction writes explicitly that we here freedom of choice here), graphics card out, RAM module repositioned, disk drives removed and unplugged all connections to the front bezel. The mainboard has an onboard reset and power button on the circuit board so that the regular power button is not needed. Also, operating the onboard button had achieved nothing. Then I took an old 350W ATX Power Supply (took out the video card and detached the drives to create some buffer) and pressed the power button. Behold - board comes to life, the numbers on the Dr.Debug (onboard diagnostic display) run through, then beeping because no installed boot media and graphics card - everything fine! Exactly the same configuration, this time with the Cougar - no response. The S550 is from November 2009, so just under 2 years old. It was handled well and did his job perfectly in the previous system. I therefore do not understand why it does not work in the new system. To me it seems as if the power supply does not react to the power-on request of the board, but I've never heard of something like this, especially something like this is sure yet defined in the ATX standard ...? In the previous system also an ASRock motherboard was installed, so the same manufacturer and it worked there. Something like that has never happened to me and I can not imagine that there could be something such as power supply incompatibilities. The Cougar did cost much and it amazes me that the second cheaper power supply makes everything without hickups, but not the Cougar. What should I do? Is there a trick I have not applied properly, perhaps? The board is brand new and cutting-edge, maybe the power supply is in some way too old? Is there a fix for the power supplies so they collaborate with current boards? What's going on? I know a lot of question but I'm also really clueless and grateful for any help!