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.