Can I put a 16x graphics card in a 4x slot and it still work?

You can run a x16 PCIe card in a x1 PCIe slot However, how the PCIe lanes are allocated are dependent on the PCIe controller and

Here is AMD's Crossfire compatibility chart to help you understand which cards will work together in crossfire and yes x16 and x4 will work fine

can you put pcie 1x in 16x slot why its not doing it in the x4 slot is the card will be pulling less power as its basically bottlenecked by only getting 14 the data sent to it

candy bonanza slot PCIe lanes are limited on consumer platforms, so odds are if you have two x16 slots, they share bandwidth, and having a GPU in one will limit