Is it safe to connect 2 seperate 4pin psu cables instead of one 8pin for the GPU?

A friend of mine built his pc yesterday and as he tried to connect the gpu, he saw that theres no 8pin gpu connector on his psu... Now he used 2 seperate 4pin gpu cables and its running fine so far.

Do you guys think that could cause any problems? I dont want him to fry it in the first days...