Can my PSU handle this?

[TheNaitsyrk]

Hello,

 

I have 2x AX1600i and I also have 6x AquaComputer Octo.

 

I have 20 fans hooked up to the Octos and I'm rebuilding my PCs.

 

The 3x Octos have:

1st Octo: 8x Noctua Industrial 3.3W 3000RPM fans plugged in

2nd Octo: 8x Noctua Industrial 3.3W 3000RPM fans plugged in 

3rd Octo: 4x Noctua Industrial 3.3W 3000RPM fans plugged in

 

Total or 20 fans and that's exactly 66W.

 

Can a molex chain handle this much power?

 

Each Octo has Molex connector and I just want to plug the chain that has 4 Molex connector on it.

 

I've heard Molex chain can handle 132W and 66W is about half.

 

I want to be sure before I even attempt this.

 

Some cables are 16AWG and some are 18AWG

[jaslion]

22 minutes ago, TheNaitsyrk said:

Can a molex chain handle this much power?

75w limit is seen as the general safe to go limit on molex so if ya wanna be extra safe just use 2 cables. You got heaps of psu connectivity for it. Else just use one cable.

 

 

[OddOod]

How certain are you on that 3.3W number? Are they 120mm fans? Because I see those at 3.6W. And if they're the 140mm fans, they're up to 6.6W (both according to Noctua website) which would work out to exactly 132W which is the theoretical max on the 12V pins of a molex connector (12V*11A=132) which is likely *why* Noctua designed the fan to draw up to 6.6W in the first place. 

Ultimately, I'd say try it, spin all the fans all the way up, feel the cables close to the PSU (yellow should be 12V if you've got ketchup and mustards, otherwise far right with the shoulders up), if it's not noticably warm wait 20 min and check again. If it's still cool to the touch, you're mint. If not, you're gonna need to use two cables. 
Honestly, I'd be surprised if it didn't work even if you're wrong about the wattage. Molex is low key bombproof and I'm kinda assuming that if it can't push enough amperage, the fans will just spin slightly slower. 

Also, can I ask *why* we're looking to power 20 fans? In a tower with dual 1600W supplies? 

[TheNaitsyrk]

5 hours ago, OddOod said:

How certain are you on that 3.3W number? Are they 120mm fans? Because I see those at 3.6W. And if they're the 140mm fans, they're up to 6.6W (both according to Noctua website) which would work out to exactly 132W which is the theoretical max on the 12V pins of a molex connector (12V*11A=132) which is likely *why* Noctua designed the fan to draw up to 6.6W in the first place. 

Ultimately, I'd say try it, spin all the fans all the way up, feel the cables close to the PSU (yellow should be 12V if you've got ketchup and mustards, otherwise far right with the shoulders up), if it's not noticably warm wait 20 min and check again. If it's still cool to the touch, you're mint. If not, you're gonna need to use two cables. 
Honestly, I'd be surprised if it didn't work even if you're wrong about the wattage. Molex is low key bombproof and I'm kinda assuming that if it can't push enough amperage, the fans will just spin slightly slower. 

Also, can I ask *why* we're looking to power 20 fans? In a tower with dual 1600W supplies? 

They aren't coloured. They're 3.3W, they're 120mm. I'll ask elsewhere you just flooded this with conflicting information and added irrelevant information to the mix 

[TheNaitsyrk]

8 hours ago, jaslion said:

75w limit is seen as the general safe to go limit on molex so if ya wanna be extra safe just use 2 cables. You got heaps of psu connectivity for it. Else just use one cable.

 

 

Right probably to be safe then, will use two separate ones. If you Google this issue there is never a clear answer and every single answer to this problem is different, super annoying. Appreciate the reply.

 

The thing I need to know still though is how much a chain can handle not a single connector within the chain.

[OddOod]

5 hours ago, TheNaitsyrk said:

They aren't coloured. They're 3.3W, they're 120mm. I'll ask elsewhere you just flooded this with conflicting information and added irrelevant information to the mix 

....okay, just trying to help my dude

[jaslion]

14 hours ago, TheNaitsyrk said:

Right probably to be safe then, will use two separate ones. If you Google this issue there is never a clear answer and every single answer to this problem is different, super annoying. Appreciate the reply.

 

The thing I need to know still though is how much a chain can handle not a single connector within the chain.

Usually the whole chain is rated for the maximum throughput of one molex connector as well they dont expect you to use it on many power hungry things.

 

Its why the general 75w limit is implied (realistically you can push 120w+ for sure but from experience that can go wrong on lesser psu's) 

 

So basically treat the chain as one header can get all or the power is devided over the multiple headers if multiple are used.

 

 

[TheNaitsyrk]

10 hours ago, OddOod said:

....okay, just trying to help my dude

Stick to the specs, not angry at you just highlighting, don't worry my dude.

 

At the moment, I have conflicting information. Online it says 132W for the whole chain, some others say 75W. Etc gets confusing

[TheNaitsyrk]

1 hour ago, jaslion said:

Usually the whole chain is rated for the maximum throughput of one molex connector as well they dont expect you to use it on many power hungry things.

 

Its why the general 75w limit is implied (realistically you can push 120w+ for sure but from experience that can go wrong on lesser psu's) 

 

So basically treat the chain as one header can get all or the power is devided over the multiple headers if multiple are used.

 

 

That my dude, is an excellent answer. I think at 66W-70W I'm safe. Thanks!

[TheNaitsyrk]

22 hours ago, OddOod said:

How certain are you on that 3.3W number? Are they 120mm fans? Because I see those at 3.6W. And if they're the 140mm fans, they're up to 6.6W (both according to Noctua website) which would work out to exactly 132W which is the theoretical max on the 12V pins of a molex connector (12V*11A=132) which is likely *why* Noctua designed the fan to draw up to 6.6W in the first place. 

Ultimately, I'd say try it, spin all the fans all the way up, feel the cables close to the PSU (yellow should be 12V if you've got ketchup and mustards, otherwise far right with the shoulders up), if it's not noticably warm wait 20 min and check again. If it's still cool to the touch, you're mint. If not, you're gonna need to use two cables. 
Honestly, I'd be surprised if it didn't work even if you're wrong about the wattage. Molex is low key bombproof and I'm kinda assuming that if it can't push enough amperage, the fans will just spin slightly slower. 

Also, can I ask *why* we're looking to power 20 fans? In a tower with dual 1600W supplies? 

To answer your other questions. It's two PCs each having AX1600i and around 50 fans each with 13 radiators in each PC.

[jaslion]

40 minutes ago, TheNaitsyrk said:

That my dude, is an excellent answer. I think at 66W-70W I'm safe. Thanks!

That and the ax1600's are hilariously overbuilt so i doubt it would have any trouble going higher. Basically same like how a 6pin pcie is rated for 75w but can do up to 150w if pushed (dont do that) the molex chain is similarly overbuilt on good psu's

[OddOod]

3 hours ago, TheNaitsyrk said:

Stick to the specs, not angry at you just highlighting, don't worry my dude.

 

At the moment, I have conflicting information. Online it says 132W for the whole chain, some others say 75W. Etc gets confusing

That's why I was explaining my maths. I try to do that because sometimes I make a mistake somewhere and that makes it easier for someone to correct me.
I always want to get better at explaining, so if I lost you somewhere, I'd be happy to expand. Or you can just take my final conclusion of It should be fine.
 

3 hours ago, TheNaitsyrk said:

To answer your other questions. It's two PCs each having AX1600i and around 50 fans each with 13 radiators in each PC.

That's *amazing*
I think I've asked for pics before, is it the one which is largely open air and has a bunch of vertical rads around it? Regardless, if you'd oblige, I'd love to see it again!

[Blue4130]

On 6/18/2025 at 3:04 AM, TheNaitsyrk said:

The thing I need to know still though is how much a chain can handle not a single connector within the chain.

You need to know for a single connector though as all of the power of the chain will go through ONE connector at the end of the line.

[TheNaitsyrk]

8 hours ago, Blue4130 said:

You need to know for a single connector though as all of the power of the chain will go through ONE connector at the end of the line.

Whilst that true I want to know all details possible, but you get my point a lot of conflicting information 

[Blue4130]

1 hour ago, TheNaitsyrk said:

Whilst that true I want to know all details possible, but you get my point a lot of conflicting information 

The rest of the chain is irrelevent though. If the wire is capable of 10,000W but the connector is only good for 75W, then you can only use 75w of "things", not 10,000. Find the information for all parts of the chain and then don't exceed the lowest.