OK, well. I don't know what your temps were before but:
20 C in idle is super low - especially that you probably have sth like 20-22 C ambient (unless you're in Australia, Brazil etc. - in which case it's even "more impossible", if I can say that...).
Right now my PC is in a 21 C room, 2600X, 360 + 240 slims, fans @ 400-500 RPM, loop freshly redone (a month ago), Heatkiller block, Gelid TIM, the PC has been on for a good couple of hrs now - the CPU it's idling at 30 C, with water at 31 C. I could understand your's idling at 25 C maybe, 26 C. But 20 C is hard to believe, really.
40 C on GPU in idle means there's sth wrong - probably poor contact / pressure, simply a mistake in mounting. If you load the GPU, does it shoot to 90-95 C in a matter of seconds? Are you sure you're using termopads for VRAM and VRMs of the correct thickness? In some (many?) cases you have to use specific thicknesses - e.g. 0.5 mm for VRAM, 1 mm for power circuitry, or this could be 0.25 m and 0.5 mm. Anyway, this often affects the pressure on the GPU chip itself, negatively, of course.