Geforce RTX 2070?

[Explicitt]

got my hands on one of these, what should my average temps be looking at CPU/GPU wise when idle and when gaming?

[Cloudy]

What CPU do you have and is it overclocked?
What CPU cooler do you have?
What exact model RTX 2070 do you have?
What case is all your parts in?

Without knowing any of those things the only thing I can say for sure is your GPU temp while on any game should below 85°C worst case, but should be well below that.

[Gru]

Regarding the GPU it depends, if it is a founders edition they usually run at higher temps when compared with the partner cards with custom coolers (MSI, ASUS, EVGA...)

Personally i like to keep my gpu at 75ºc(maximum) under load but it's a different model (MSI 1070ti). Your's shouldn't be much different anyway. But bear in mind that if it is a founders edition it may run at higher temps but not by much.
At idle it should be something around 35ºc/40ºc. But you should pay more attention to the temps under load not in idle unless the idle temp is something way higher than 40/45ºc

Concerning the cpu yeah we need to know the model to be more precise about it.

[Monk]

For max speed, under 40c, though, that needs a big custom loop, for safety, it will throttle at 85c to protect itself, so anything under that is fine.