One question about MRT

Hi,

I have a question about MRT.

Let's say i have a shader with MRT output, something like this:

struct PixelOutput
{
	float4 color0 : COLOR0;
	float4 color1 : COLOR1;
};

PixelOutput pixelShader(Input in)
{
	float4 color = 1.0;
	
	PixelOutput output;
	output.color0 = color;
	output.color1 = color;
	return output;
}

But what if i just have only one RenderTarget is active? What the GPU would do when it couldn't find enough RenderTargets as it should have?