You were right about the connectors. As I checked the components I found out it's actually a 6+2 pin connector. Does that make any difference tho?
6+2 pin connector is an 8-pin connector that works for 6-pin as well.
Thanks for advice but I can't help myself but to ask ... Why do you have such an opinion on this particular PSU? It has no rating on amazon which might be sketchy but i'm running this component for at least 7/8 years without any problems. Here (
https://www.amazon.co.uk/LC-Power-5...=lc+power&qid=1594383354&s=electronics&sr=1-4) is almost the same PSU with quite a nice review and only difference of it being a 2.3 V instead of formerly mentioned 2.2 V.
Both LC PSUs you linked cannot provide all their power via the 12V rail, which is the most important in PCs since the Pentium 4 era. This tells me they are using a design from before that era - such designs are poor in terms of efficiency, and usually in terms of protection circuitry. Most importantly, designs of this age are well-known for, let's call it... overstating their capabilities, meaning they cannot hit the output they claim. (This was before PC hardware reviewers started rigorously checking PSUs and calling out manufacturers for such dishonesty.)
Effectively, those LCs are not 550W PSUs, they are 364W and 400W PSUs... except they aren't even that, because the math on their spec labels doesn't add up. The first one claims twin 12V rails of 19A each, which equates to 456W - a helluva lot more than 364W. Similarly, the second claims 18A and 20A, which again would be 456W - yet it only guarantees 400W. Hmmm.
The final nail in the coffin is that no respected PC hardware review site has ever covered an LC PSU. You would imagine that if LC was confident in the capabilities of their products, they would be happy to supply review units - because after all, a good review is free publicity. Yet they have not done this - why do you think that is?
In contrast, look at a modern 450W Bronze PSU from a well-respected brand:
https://www.corsair.com/uk/en/Categories/Products/Power-Supply-Units/Power-Supply-Units-General-Purpose/CV-Series™/p/CP-9020209-UK#tab-tech-specs It can provide 432W of its 450W (96%) of its output on the 12V rail. It is Bronze-rated with one more PCIe 8-pin connector than the "550W" LC Bronze unit, despite having 100W lower output. It has been reviewed by a respected reviewer
https://www.tomshardware.com/uk/reviews/corsair-vs450-power-supply,6076.html which considers it decent at best.
If that Corsair unit is merely decent to someone who knows the innards of PSUs and what makes them good or not, what do you imagine that person would think of these LC units?
At the end of the day, an LC unit will be fine in a system that doesn't push it very hard. But an RX 580 will push a PSU a lot harder than the 550 Ti, and old PSUs of questionable quality tend to behave badly when they're pushed hard. Depending on how good or not the aforementioned protection circuitry is, that might involve killing every component in your system... or it might, quite literally, involve fire.
Would you trust an electrician who tells you that 2 x 2 = 6? If not, why would you trust LC?
