What are the impact on underpowering my motherboard/graphic card?

Question

I recently had to change my PSU and the one that was given to me has not enough power cables to fully plug every plug in the motherboard and the graphic card. It seems to work just fine though, and it's been going on for over a year now.

I was just wondering if it had any impact on performance, durability, or anything else to underpower my hardware like that?

The PSU has a lower power limit (600 vs 750) than the older one, and therefore has less power cables. Games run fine (though i can't really compare, i didn't have the old one for long), everything is good, and i've never really had bluescreens or anything of the sort.

What happens if I run a stress test? is it risky? or will it just slow down? I've been told that it might burn because the motherboard would ask for more energy than the cable can supply. I have absolutly no clue on what can happen and on top of being curious, i'd like to know if i'm taking risks with my hardware here ^^

Thanks for your time ! Looking forward to your answers !

Answer 1

The PSU should be protected against overload. The worst (practical) thing that can happen is that you blow a fuse on the PSU. The worst theoretical thing is that your PC can catch fire, or blow a fuse in your house's electical system. Most likely the PSU will just switch off when it detects an overload, but it depends on the model. However, the PSU might deliver more than enough power for your particular setup.

One reason to ship with a more powerful PSU is because most PSU's work most efficient at around 80% load. If, for example your PC's maximum power usage is 590W, a 600W PSU would still work, but not be as efficient as a 750W.