3200mhz(void CPU/MB warranty) ram downclocked to 2666mhz will void corsair warranty?

I plan to buy CMK64GX4M4B3200C16 for my new PC.

Because XMP will my void CPU/MB warranty, so if I turn XMP and downclocked to 2666mhz will void my corsair warranty?

No, running the memory at a slower speed and theoretically lower voltage will not alter Corsair's warranty on the memory. However, read your motherboard and CPU manufacturers' warranties carefully. Generally, any setting above JEDEC 2133 MHz is considered "overclocking" from their perspective, despite the rather hypocritical marketing tactics used on most motherboard websites. It is also difficult to imagine how a motherboard manufacturer who makes their board XMP 2.0 compatible, could then make that grounds for warranty exclusion, but I am not offering you a legal opinion today. I have never heard of Intel or AMD denying a memory claim because of DRAM clock speeds. If your memory frequency is too high or timings out of wack, the system crashes, maybe your OS becomes corrupted, but it doesn't fry the internal memory controller on the CPU. You need voltage and current to do that. That is something under your control.

Yea, manufacturer marketing are Troll, they need clarify which BIOS setting change will void warranty and need warning before you change.

Intel or AMD both guarantee CPU Memory Controller can support 2666mhz ddr4 on this year.

I still not know will MCE (Multi-Core Enhancement) will void my CPU warranty....

Since every single board maker puts it in their BIOS systems, it would be hard to make this enforceable, particularly when most boards come with it switched on by default. That is an issue between Intel and the board makers. I have a hard time seeing Intel wanting to drag you into the middle of it. You have to decide what you are comfortable with, but I don't hear a lot of stories about normal people running into issues with these kinds of things. It really isn't in their best interest to pursue matters in this way either. Set your Vcore to 1.65v and that is a different matter.

I still not know will MCE (Multi-Core Enhancement) will void my CPU warranty....

Since MCE is enabled by default for most boards, that would make CPU warranty pointless. In general you won't have trouble with warranty claims as long as you don't outright kill the components with extreme high currents/voltages/temperatures (and/or visible damage).

 

Why would you even buy XMP enabled memory rated for DDR4-3200 CL16 and then only use it downclocked in the first place?

I would find it insane if motherboard manufacturers add XMP to their BIOS and yet make it against their return policy.