Are you using it for mining?
If it's a modular PSU you need the right cables, some of them are not "standart". Sometimes from one brand fit to another brand but not always.
You won't blow your card off but you can damage both the card and PSU if you use only one channel to power the cards. That means that if you use only one group of cables and buy some extenders to connect the other cards, the power provided trough that channel (group of cables) might not be enough for that power consumption you have. If you cannot find the right cables ( I assume that the PSU is Modular) then you can trick the system and use MOLEX or SATA adapters like those:

^MOLEXhttps://cdn-reichelt.de/bilder/web/xxl_ws/E201/DELOCK_83703_01.png

^SATAhttps://cdn.shopify.com/s/files/1/0114/5339/9097/products/HTB1t2k4SXXXXXX6aXXXq6xXFXXXx.jpg?v=1575536580

Always use 2-to-1 adapters (those type from the pictures above)  to be sure that you have enough power and never use the same channel to power two cards.

At the end you have left with 700 - 375 = 325W which, depending of the processor type, most likely should be enough to power the rest of the components you have.

Pinouts on different PSUs are not same, so seller might have a point. Even within one brads pinouts might differ from model to model.

Are you talking about the same bee 🐝 project that people are mining through the app dashboard everyday?? Look the image down below, is this what you talking about?

https://i.imgur.com/auY1zf8.png

If Yes the project is absolute nonsense, what I'm surprised about is who people get so hooked to this project as if they are going to make huge money mining it everyday, the project has no reasonable use case to begin with lol

Don't bother buying the RTX3060 because Nvidia have locked it's mining potential, it's a waste of money buying that card for mining, better buy RTX3060Ti, RTX3070, or higher, you can also consider AMD RX5700XT this card rocks, high hashrate at low power consumption

just checked for you. Best algo for you is etc. looks like it gives 17.5mhs on eth based algorithms. 17.5mhs on etc right now giving 0.74$. nicehash does not support etc you will need wallet and and pool for etc. with 28 sols on zhash you are making 0.70$. so there is no point to switch.

The gtx970 got some speed but the let down will be it's memory which is 4gb I believe so the best option here is to mine profitable coins that still allows 4gb memory, for example you will make good gains from conflux (octopus algorithm) and also bitube (cuckaroo29b), spend your time on these two algorithm instead

it has 3.5 older gen memory and 0.5 newer gen at the time, so it's technically 4gb

i never had gtx970 but i heard it has only 3.5g memory which is not enough for eth even zombie mode will not help. current eth dag is more 4g.
Try beam and etc, if it is low then zhash only coin left for that card right moment.