Something may have jostled loose or become mispositioned during the case swap..Reseat the RAM..Also, the memory controller is built into the 4790K CPU, reseat the CPU too if reseating the RAM doesn't help..Roll from there.

You state one bios will not post at 1.65 volts but another will. I would try clearing the cmos while in the first bios or even reflashing that bios.

Just from swapping cases, huh?..Weird.
 
Just for kicks and if you haven't yet, I would populate only 1 bank at a time and see how it rolls..Bank 1 is physical slots 1 and 3, with 1 being the closest to the CPU..Bank 2 is physical slots 2 and 4.
 
Make sure the frequency, timing and voltage is set manually (not an X.M.P. profile) to the RAM mfgr's specs and with a 2N CMD (Command Rate) instead of 1N which it may default to.
 
If still no joy, take the mobo out of the new case and fire it up on a table and see if that matters.

So if you manually set the voltage to 1.65v it still shows 1.43v?

Hmm. What happens if you try to set it to 1.70 or 1.75?

Well did the test, use one slot and memory at the time, no luck there. increase voltage to 1.70 and 1.75, no luck there. But this time I got it to post and run stable at 2133mhz the voltage at Auto. Did try all setting on bios 1-2-3, it appears that 1 and 2 can't get past 1600mhz. and on 3 is stable at 2133mhz, I did reflash bios and still same issue. Sound to me like a bad bios chip. Any suggestion? 

It sound like that would work, I am going to try that tonight see what happens. Thanks again Sajin!

It might also be worth trying Sajin suggestions on one stick at a time. You one of the sticks isn't stable while the others are. 

Set both VSA & VCCIO to 1.2v.

No problem.

kougar, I am aware of the info on CPU-Z the issue I have I can't get it pass 2000mhz at 1.65v while the memory are spec out for 2400mhz at 1.65v, when I increase to 2400mhz 1.65v it gives me error code on the bios 55 no memory install. Yes I did try all the XMP files on the info on CPU-Z none of them works for me, Is a shame the I bought this memory to run them at 2400mhz, I can only run them 2000mhz while on the other case was running perfect at 2400mhz. Just can understand what could be causing this problem. Sajin I did as per your comment (VSA and VCCOIO at 1.20v) and had no luck with it. Any other suggestion, Thanks to you all for the help.

I like to do that, but is my son computer and he need it for college, I can't shut it down or pull the motherboard out for a long period of time, hoping I solve this problem without pulling thing apart. Is running good, but sure like to get it at 2400mhz. I will be building him a new one in a couple month from now. 

Sajin, I had it running before on the other case at 2400mhz 1.65v without any problem.

Sajin, Is that possible?

Sajin
Yes, as the cpu is only spec'd to handle 1600. Anything over 1600 is overclocking and isn't guaranteed.

This is especially true if the user or the motherboard itself are overvolting the IMCs, or the RAM above 1.65v. Subzero benchers regularly burn out or damage the IMCs on Intel chips from pushing the memory clocks to the limit. It is why I am leery about automatic overclock settings on boards, it is in mainboard manufacturers best interest to be generous with the 'auto' voltages to ensure stability even on below-par CPUs. Still weird it occurred during a case change...  same PSU right? You could try remounting the CPU in its socket as maybe one of the pins isn't making quite as good contact after the jostling? Far-fetched guess though.
 
At any rate 2000Mhz vs 2400Mhz isn't tangible outside of benchmarks, I wouldn't worry to much about it. You can almost certainly tighten the memory timings manually and that will get back most of the performance difference anyway. Dropped mine from CL11 to CL8, then kept dropping all the subtimings until I found the limits of stability. I'd recommend ya just go this route, especially since you're building a new one soon.