For our manual overclocking tests, we used MSI Afterburner. Our best results are as below.
As for overclocking, the first thing to note is the power limit for the RTX 4080 can be raised, but not by nearly as much as the RTX 4090. The 4090 can be set at up to 600W, whereas the 4080 maxes out at 355W.
I don't see that as a big problem as the 4080 doesn't appear to be power limited in my testing, and we were still able to add 205MHz to the GPU and a whopping 1620MHz to the memory, bringing speeds over 25Gbps!
This brought the GPU's average operating clock speed up to 2934MHz, so it wouldn't push quite as far as the RTX 4090, but it's still a decent improvement.
Frame rates increased by 8-9% thanks to this overclock, which is not too shabby and is fairly similar to what we have found with the RTX 4090.
Power draw did also increase, as expected, but only by around 26W, which is an 8% increase, so that is in-line with our performance gains.