I attempted to install a Sapphire Radeon HD 5850 graphics card on an older Epox 9NPA+ Ultra motherboard. This motherboard has a X16 PCI-E port as required and my system also has an 850W Corsair PSU. After installing the card and connecting both 6 pin PCI-E power cables the monitor remains blank and will not display the POST screen on attempting to boot. The motherboard also displays error code 25 on its LED which is only defined as "Reserved" in the manual. Any advice would be most appreciated.
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Only thing that I can think of causing this problem would be a combination of the board being a bit older, not being pcie 2.0 , and that the Epox 9NPA+ Ultra is using an NVIDIA chipset.
Many cases that ATI's card can't work properly with NVIDIA chipset. have u try update your motherboard?