12VHPWR 600W cable vs stock daisy chain

[chilik49]

Hello, I have recently purchased and built my new PC with the RM850x PSU, which came with only 2 PCIE cables.
I got an RTX 4080 Super and after lots of research due to being scared to daisy chain I came to the conclusion that it will probably work just fine especially without any crazy loads. 
That being said I did find the 12VHPWR cable that corsair offers very appealing, both because it looks way better than the thick cluster of stock cables with the card's adapter, and because everyone recommended it instead of daisy chaining.
My question is, the 12VHPWR cable has 2 8 pin connectors just like my current setup, and other than the direct 12 pin GPU connection bypassing the need for the adapter I can't find any other difference between the stock cables and this one. In that case, why do some people recommend it and avoid daisy chaining? Does this cable just have that much better of a wattage spec and connectors that can handle way more than the stock ones? Does it really eliminate any concern one might have with daisy chaining? After all, it's still the same 2 8 pin PSU cables or so it would seem to me..
 

[LeDoyen]

the 8pin PCIE connector is spec'ed at150W even if the cable can take more (in practice, the connector can do more than 150W, but that's the value they must go by).

So when you use the 2x8 to 12VHPWR cable, you basically can pull 300W per connection on the PSU.

So yes it has higher wattage handling capability and looks better, and doesn't induce that little voltage drop at the extra conection the squid cable has.

 

[chilik49]

15 hours ago, LeDoyen said:

the 8pin PCIE connector is spec'ed at150W even if the cable can take more (in practice, the connector can do more than 150W, but that's the value they must go by).

So when you use the 2x8 to 12VHPWR cable, you basically can pull 300W per connection on the PSU.

So yes it has higher wattage handling capability and looks better, and doesn't induce that little voltage drop at the extra conection the squid cable has.

 

But wouldn't it be 300W in both cases then? It's still 150W per 8 pin connected to the PSU.

I'm not sure how the wattage distribution works with the card's adapter, but I imagine it's pretty equal between the 3 connections. In that case since one is a daisy chain I can see it posing a possible issue with 2/3 of the watts coming from a single 150W spec'ed cable (330 x 0.66 = 220W), so in theory it could be a little bit over.

I'm not even accounting for the 75W coming from the PCIE slot on the mobo, so it seems like with a daisy chain I would only be pulling about 50-60W over the cable spec, and I've heard especially with good models like the RM850x corsair cables are usually overspec'ed. Should I still avoid this extra wattage and get the cable? Thanks for the reply!

[LeDoyen]

It's purely to conform to the PCIe spec that they put one PCIE connector for each 150W.

The connector on the PSU end id not standardized so it can take as much power as the manufacturer makes it.

For Corsair, they take only two 8 pin for the whole 600W, and the connector at the other end is 600W.

The real question is, why would you want to put 150W connectors in between. The only answer is if your PSU has no 12VHPWR conector, or you don't want to invest in a cable to replace the "squid" adapter.

In the end, the 4080 S is a 320W card, so using a pigtail cable to connect the 3rd PCIE plug would be fine i guess, it'd be only a small overload. But it still makes a mess, that's a lot of cables and plugs hanging off the card, and if you wanted to get a 3rd cable to plug 3 direct connections to the PSU, might as well get the native 12vhpwr cable.

For the PCIE slot power, that usually doesn't go to the core but to the rest of the board.

Personally i'd still get the proper cable, just to get rid of the clutter, and potentially less weight on the connector depending on how the case is laid out.