One thing to look at is that 6800 is based on navi21 just like 6800xt and 6900xt.
3080 and 3090 Are based on 102 die, but 3070 is based on 104 die!
So you should compare 6800 to 3070ti that is Also using 102 die and use about 300w based on ”leaks”... Lets see the real Numbers when that gpu is released.
You should compare normal 3070 to amd 6700xt, when it is released, because it is based on navi22 chip. But now because neither 6700xt nor 3070ti Are not yet released people make these odd comparisons because They have nothing else to compare with!
all in all 6800 is subtantial faster than 3070... on the other hand 3070ti will be really close, maybe faster so Lets wait few weeks and see who takes the upper middle range in speed and power usage wise!