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#11
BIOS i do not see how on support page or manual, each PC are different on how HP logo screen if shown will sometimes tell you, can be either Delete key, F8, F9,F10,F12 i am not sure. Thought you did disable the integrated card. I would not try changing the boot order then will not be able to boot. I would take out that bought card as a test and try booting just to see if it is faulty in any way and will be using the integrated card then.
Either a power issue, a faulty card or incompatibility with something if it works with the integrated card.