Can you use 1 MOLEX to power an RX 570?

[kontex]

So I need a GPU and for price reasons I'm considering AMD over Nvidia.

So I'm looking at the RX 570 or the RX 480 but my PSU is non-modular so I need 3rd party power connectors. I already have a Molex to 6-pin but the cards need an 8-pin I believe.

Would I be able to use a single Molex to power the card?(I don't have any spare Molexes on my PSU).

[manikyath]

if you dont have the required connectors on a power supply, chances are you dont have the required wattage either

[Sakkura]

I don't see what non-modular has to do with it?

 

Anyway, if the power supply doesn't have the needed power connectors, the proper solution is to get a new power supply.

[Bananasplit_00]

sounds like you need a new PSU tbh

[Firewrath9]

I would not, as molex is very fragile and only a friction mount, besides, molex is rated for like 3A on the 12v rail, and 570s can push 150+ watts.

[kontex]

I have a 600W PSU so I should be fine on that and I don't really plan on OC(not much)

And if I could get a new PSU I would but cash is a problem as always

So 2 Molexes for a single 8-pin???

[mariushm]

The card consumes up to around 175 watts , if you don't overclock it. 

It will take around 50-60w through the pci-e slot, and the rest of around 125w come from the pci-e 8 pin connector.  It has to be 8 pin because a video card is only allowed to take up to 75w from a 6 pin pci-e connector.

 

The contacts inside the molex (hard drive) connectors are rated for 5A, so this means though each molex connector you should NOT take more than 5 x 12v = 60w.

If this value is exceeded by a significant amount, the connectors may overheat and the plastic housing can melt or even burn.

So, you MUST use an adapter with TWO molex connectors to power you video card, this way each molex connector will transfer approx. 60-70w to the video card, which is just a tiny bit over the rating of the individual molex connectors so it will be relatively safe.

 

In addition to that, you should be aware that a whole chain of molex connectors from a power supply is transferring 12v to those connectors through a single pair of wires, which means you should not exceed that pair's current rating, which is around 12-14A for AWG18 wire. So ideally, if you have two chains of molex connectors from the power supply, you should connect one half of the  2xmolex -> pci-e adapter to one chain and the other half to another chain of connectors.

Basically, you want as many pairs of 12v+ground wires all the way between the power supply and the video card. Normally, the pci-e 6pin and 8pin uses 3 pairs of wires, the 2xmolex -> pci-e adapter reduces the number of pairs to a maximum of 2 which is already barely safe if the video card gets close to the maximum of 150w a video card is allowed to take. If you connect both molex to a single chain, you're further reducing down to 1 pair of 12v+GND wires.

 

Make sure the power supply is actually capable of providing the power for the video card AND the processor. Reserve 100w or so for processor, motherboard and other things... s make sure the power supply can actually provide around 250-300w on the 12v rail (from where power hungry components take power).  That's at least 250w / 12v = ~21A  ... 300w / 12v = 25A ... the power supply should have these numbers printed on the label.

 

You can also reduce the video card's power consumption from the driver, from the overclocking page. you can lower the power limit by around 3-5%, which should reduce the power consumption by maybe 15-25w and you'll get just a bit of performance drop, maybe 1-3%.

[Sakkura]

6 minutes ago, NoobKing said:

I have a 600W PSU so I should be fine on that and I don't really plan on OC(not much)

And if I could get a new PSU I would but cash is a problem as always

So 2 Molexes for a single 8-pin???

What 600W power supply is it? If it doesn't even have a single 8-pin PCIe connector, chances are it's a really bad power supply.

[kontex]

1 minute ago, Sakkura said:

What 600W power supply is it? If it doesn't even have a single 8-pin PCIe connector, chances are it's a really bad power supply.

You got that right lol

But no seriously I wasn't going to cheap-out on the PSU but...ehhh got screwed

[kontex]

From what I'm seeing (AMD's website) the recommended PSU wattag for the 570 is 450W,on that end I should be fine right

[Enderman]

A 600W cheap chinese PSU is not the same as a high quality brand name 600W PSU.

A crappy PSU will light your house on fire before you even reach half of its rated wattage.

So it really depends on what model of PSU you have.

[kontex]

Yeah it's some chinese box of tin but 600W should still be able to handle the 570 right?

I just don't see the issue being there

[mariushm]

1 minute ago, NoobKing said:

From what I'm seeing (AMD's website) the recommended PSU wattag for the 570 is 450W,on that end I should be fine right

Dude, AMD and nVidia have to cover their asses and try as much as possible to reduce the RMAs and all that.

 

Those recommended PSU wattages have nothing to do with the actual power consumption, they put there a number which reduces the risk of people combining these video cards with a power supply that lies on the label and can't actually deliver what it advertises.

 

You have those chinese no-name firecrackers that print 400w on them but in reality they can barely output 200w on 12v.

Or, you have power supplies based on older designs that reserve a portion of their output to 3.3v and 5v, and the rest to 12v ... for example, this Raidmax 400w power supply can output 400w in total, but only 336w on 12v : https://www.newegg.com/Product/Product.aspx?Item=N82E16817152061

 

So just to be sure people don't combine these video cards with shitty power supplies, they push people into higher wattages hoping they'll get something decent.

 

You know the card will use at most 175 watts ... even if you don't know, you should know a video card is only allowed to consume 60w from slot and 75w from a 6pin or 150w from a 8 pin connector, so worst case scenario your card would consume 60w + 150w = ~ 210w

If you know approximately how much power the rest of your components use, then you can pick a good power supply and be confident it would work. 

 

For example, a RX 570 will run even on a 350w power supply like this seasonic 350w psu: https://www.newegg.com/Product/Product.aspx?Item=N82E16817151075

It's a brand name power supply, I know it doesn't lie when it says it can do 325w on the 12v

I can combine this with a Ryzen quad core cpu which will consume up to 50w or so, and the motherboard and mechanical hard drive won't use more than around 25w so overall, the whole PC won't use more than 250w which is less than 325w, so it will work.

Of course, it wouldn't work with a 6 core or 8 core Ryzen, or for any kind of overclocking.

 

Anyway, good quality power supplies are cheap these days, you can spend 60$ for a 650w GOLD efficiency psu from a brand name if you're in US... no stress

[Enderman]

14 minutes ago, NoobKing said:

Yeah it's some chinese box of tin but 600W should still be able to handle the 570 right?

I just don't see the issue being there

The issue is that it is actually NOT 600w, so if you want to risk a house fire then go ahead.

[kontex]

OK so I did some math and made my whole system on pcpartpicker and my whole system(with an RX 570) would draw 450W

DO you think this PSU will handle this (no OC on CPU,GPU...) ? 

[mariushm]

What psu are you talking about, you keep asking but don't say what you have ....  (i have signatures and extra crap disabled, in case it's listed there).

Take a picture of the label or say the brand and model at least, if it can be googled..

[xg32]

7 minutes ago, NoobKing said:

OK so I did some math and made my whole system on pcpartpicker and my whole system(with an RX 570) would draw 450W

DO you think this PSU will handle this (no OC on CPU,GPU...) ? 

if the other 2 posts wasn't clear enough, do not hook a molex up to that video card or risk a melted connector into a possible electrical fire->house fire. Not sure if trolling at this point

 

https://www.newegg.com/Product/Product.aspx?Item=N82E16817139199&Description=corsair psu&cm_re=corsair_psu-_-17-139-199-_-Product

 

even has a 20dollar rebate.

[kontex]

7 minutes ago, mariushm said:

What psu are you talking about, you keep asking but don't say what you have ....  (i have signatures and extra crap disabled, in case it's listed there).

Take a picture of the label or say the brand and model at least, if it can be googled..

Sry no way to know,text is in chinese I can only give you a barcode if it helps

 

 

600w PSU,2 Molexes and a single 8pin connector for a standard Non-OC version of the RX 570,can I do it

[mariushm]

No, your psu must have a label.  if you're looking on the back of your pc where the power cable goes in... that's not the right place. Look inside the pc on the side of the power supply case, there should be a label with some numbers.

But based on the number of connectors, it's not a 600w, it's at best a 400-450w power supply.

 

 

[mariushm]

13 minutes ago, xg32 said:

if the other 2 posts wasn't clear enough, do not hook a molex up to that video card or risk a melted connector into a possible electrical fire->house fire. Not sure if trolling at this point

 

https://www.newegg.com/Product/Product.aspx?Item=N82E16817139199&Description=corsair psu&cm_re=corsair_psu-_-17-139-199-_-Product

 

even has a 20dollar rebate.

His profile says he's in Bosnia. We don't have such rebates in most EU countries even, not to mention "poorer" countries like Bosnia.

And brands like Corsair are in general more expensive than others here (paying for brand name)

[kontex]

The label is accesable if I rip the whole PSU out of the case, it's 12:30AM I'm not doing that right now

2 molexes and 3 sata power connectors

[Sakkura]

27 minutes ago, NoobKing said:

OK so I did some math and made my whole system on pcpartpicker and my whole system(with an RX 570) would draw 450W

DO you think this PSU will handle this (no OC on CPU,GPU...) ? 

It's impossible to say. Some of these no-name PSUs will fail spectactularly when delivering less than half their rated wattage, possibly taking other hardware with them. It's a risk I would never, ever want to run with my own hardware.

[kontex]

OK so I'm stuck with my intergraded hd 4000 for the next year or so

thanks for the advice

[mariushm]

Or try to find a video card that uses less power, for example a GTX 1060 will only use around 120 watts.  A GTX 1050 and GTX 1050 ti will go up to around 75w... these will work with just one molex connected to the power supply

On AMD's camp, RX 560 also uses only around 80 watts, so again you could use a single molex connector.

[kontex]

Guess I'll just have to go scavanging for a 1060 then lol