Good, Easy to install Cpu cooler

Most aftermarket coolers use a backplate. About the only ones that use pushpin retention like the stock cooler are aftermarket coolers which resemble the stock cooler in looks, size and cooling performance. The more common aftermarket coolers are larger 'flower' shaped like many of the zalman or tower style and since they're quite a bit larger and heavier need a more solid mounting method involving a backplate. For overclocking, you're going to want a decent cooler of some sort and unless there's a rare good cooler out there with pushpin type retention I'm unaware of you'll probably have to use one with a backplate. I'm guessing your motherboard tray is solid (no access cut out in the back) and it will mean removing your motherboard which is why you're looking for one with pins similar to the stock one.