Question Molex to PCIe limit.

[LauroSalvatore]

How many watts of consumption from the GPU is too much when using a Molex to PCIe adaptor that would be unsafe? If I have a 600 watts 80 plus bronze PSU with only one 6pin pci-e connector and I want to use a MSI GTX 670 OC (requires 2x6 pin connectors), would it be safe? Or would the needs of the GPU be too much for the PSU to handle through Molex? I've read somewhere that Molex can give 40 watts, so if the PCI-E x16 3.0 slot can give 150 watts (limited to 75 by the GPU manufacturer), and the 6pin pci-e connector gives 75 watts, would it be safe to try to get the missing watts from the molex to PCI-e adaptor?

And does the GPU draw only the needed amount of watts from the molex or it takes the whole 40 watts from it? In case I'm not wrong and they actually provide 40 watts, either way, would it take only how much it needs or would I risk frying the GPU when using Molex to PCI?

P.S. I've read in some pages that the GTX 670 OC uses 170 watts, but on some other pages I've read that it uses 190, and on other pages I've read it uses over 200 watts, so... How much does it really use?
P.S.2. I'm pretty sure that my GPU is the MSI GTX 670 Power Edition, not OC.
P.S.3. If I just underclock it would it be enough?
I know it's pretty messy, I'm sorry D:

 

[DSzymborski]

Do.

Not.

Use.

An.

Adapter.

Ever.

Well, I wouldn't say ever. For example, if your family is taken hostage by a madman and the surprising demand is for you to run a GPU using molex adapters, that would be a typical use scenario for an adapter. But usually this not the case.

Nobody's saying to buy some crazy 1000W Platinum. But the least expensive PSU worth purchasing, when trying to run a discrete GPU that requires supplemental power, will typically be a Corsair CX (without the green lettering).

If you can't afford a $45 PSU to safely run your GPU, how would you be able to spend the $120 to replace the performance of your GTX 670? Or even more; adapters are a common area for fires to start, in which case you'll be shopping for a lot more than a new PSU or a new GPU.

You have a total of hundreds of years of experience with these issues counseling you to not do what you would like to do. USAFRet alone has helped people numbering in the tens of thousands.

I'd think long and hard about just how expensive a cheap solution frequently is.

 

[King_V]

I will also chime in . . do NOT use a Molex -> PCIe adapter. EVER.


The ONLY adapters that are acceptable are:
8-pin PCIe -> 2x6-pin PCIe.

This is because the power draw is the same. The 8-pin is rated to handle up to 150W, and each 6-pin is rated to handle up to 75W, so an 8-pin to 2x6-pin is acceptable.

But a Molex -> PCIe adapter? No.

DON'T do it. Get a different PSU.

 

[NightHawkRMX]

Well, the 12v rail has 45A, which is about as much as a decent 550w. It should be able to power the adapter, however, maybe not reliably. Even if the PSU could supply the required current through the Molex connector, the wires or the adapter might melt as they are not designed to pull many watts.

Again, If the PSU was designed to power 2x6 pins reliably, the manufacturer would have equipped the psu with those connectors.

 

[-Fran-]

Well then, I've got plenty of answers so I have quite more knowledge over this particular topic. And due to the lack of answers over my last question I'm guessing the CoolerMaster MWE 550W isn't good enough either. So I'm gonna take in mind Yuka's proposal and Allan's risks. First of all I'm gonna ask one last question while giving more info about my PSU. Actually, I'll post an image of it:

https://imgur.com/3IUkDjb

View: https://imgur.com/3IUkDjb

With these specifications in mind, would it be able to handle the adaptor from Molex to PCI-e?

When it comes to Molex connectors, I have both of them free, none are being used, and they are in the same cable.

In case it doesn't work. Or it simply is a really bad idea, I'll just go for the CoolerMaster MWE 550. Guys, I'm not rich nor I have won the lottery. lol

I don't recognize the branding of the label there, but if you just want to go by the numbers and not the internal quality of the components, that information tells me the PSU is what I called "single rail" design. This means, all the 12V power you PC needs will come from the same source within the PSU. This has some advantages and disadvantages I can't remember from the top of my head, but I do remember Toms had an EXCELLENT article about this very same topic a few years ago that explained in great detail each approach. That being said and keeping it a tad short: single rails are more dangerous than multi as it will depend on the manufacturer of the PSU how they distributed the cables and their protection mechanism. This is to say, if you have, say, 4 cables (usual config for ~500W single rail) coming from the PSU that are meant to feed the GPU (6/8pin molex), CPU (4/8pin molex to the motherboard) and other devices (sATA and 4pin "fat" molex) and by chance you decide to use an adapter on a single cable and feed everything from it, then you would be effectively trying to transit ~500W over a single set of cables. That's a really BAD idea. Now, the big question I'd have is how the PSU maker decided to split each cable's protection mechanism over them. They can be lazy and just lay them down "as is" or properly build each lane it's own "safety line". What are the chances of that with a no-name PSU brand? Oof, almost non-existant (and here is where I would agree with the "get a new PSU" from everyone). If you have a way to get the tech sheet of this PSU and make sure they did the due diligence and have each lane for the cables protected, in case the PSU decides to die on you, or the GPU/CPU decide to suck more juice than really safely allowed, it would shut itself before self-immolate (which some single-rail models used to suffer from!). This is where my advice of: if you were to use the adapter, make sure you use it in an isolated lane (cable) comes into play; this way you minimize the danger of a single cable going over-spec with the power going through it.

I hope that helps you better understand the whole context of what everyone si pointing out to in your thread and why the massive majority is trying to make you buy a new PSU instead of trusting your current one. I'm being a bit more neutral and trying to make the argument for both sides. I don't like witch hunts.

So, as a summary of everything I've said and final word from me: if you can spare the 670 (or the PSU), then give it a try, but keep an eye on how it behaves. If the PC turns itself off or any other weird behaviour like that, change the PSU right away. Best case scenario: you save money; worst case scenario: you need a new PC

EDIT: https://www.tomshardware.co.uk/power-supplies-101,review-33299.html

Found it!

Cheers!

 

[LauroSalvatore]

I don't recognize the branding of the label there, but if you just want to go by the numbers and not the internal quality of the components, that information tells me the PSU is what I called "single rail" design. This means, all the 12V power you PC needs will come from the same source within the PSU. This has some advantages and disadvantages I can't remember from the top of my head, but I do remember Toms had an EXCELLENT article about this very same topic a few years ago that explained in great detail each approach. That being said and keeping it a tad short: single rails are more dangerous than multi as it will depend on the manufacturer of the PSU how they distributed the cables and their protection mechanism. This is to say, if you have, say, 4 cables (usual config for ~500W single rail) coming from the PSU that are meant to feed the GPU (6/8pin molex), CPU (4/8pin molex to the motherboard) and other devices (sATA and 4pin "fat" molex) and by chance you decide to use an adapter on a single cable and feed everything from it, then you would be effectively trying to transit ~500W over a single set of cables. That's a really BAD idea. Now, the big question I'd have is how the PSU maker decided to split each cable's protection mechanism over them. They can be lazy and just lay them down "as is" or properly build each lane it's own "safety line". What are the chances of that with a no-name PSU brand? Oof, almost non-existant (and here is where I would agree with the "get a new PSU" from everyone). If you have a way to get the tech sheet of this PSU and make sure they did the due diligence and have each lane for the cables protected, in case the PSU decides to die on you, or the GPU/CPU decide to suck more juice than really safely allowed, it would shut itself before self-immolate (which some single-rail models used to suffer from!). This is where my advice of: if you were to use the adapter, make sure you use it in an isolated lane (cable) comes into play; this way you minimize the danger of a single cable going over-spec with the power going through it.

I hope that helps you better understand the whole context of what everyone si pointing out to in your thread and why the massive majority is trying to make you buy a new PSU instead of trusting your current one. I'm being a bit more neutral and trying to make the argument for both sides. I don't like witch hunts.

So, as a summary of everything I've said and final word from me: if you can spare the 670 (or the PSU), then give it a try, but keep an eye on how it behaves. If the PC turns itself off or any other weird behaviour like that, change the PSU right away. Best case scenario: you save money; worst case scenario: you need a new PC

EDIT: https://www.tomshardware.co.uk/power-supplies-101,review-33299.html

Found it!

Cheers!

Thank you so much for letting me know all of that, I really appreciate it, it's really helpful to get a better understanding at how a PSU works. I've seen in a lot of places people arguing over single or multi railed PSU and I just didn't know what they were, at all, nor what was its purpose. Now I know.
I'm pretty sure the brand is cheap af. What I don't know is how their PSU is built. It's a Golden Field ATX-600W. I've had an overlook of it on Google but didn't really find out anything that could let me know how it's built nor its specifications.

 

[NightHawkRMX]

Thank you so much for letting me know all of that, I really appreciate it, it's really helpful to get a better understanding at how a PSU works. I've seen in a lot of places people arguing over single or multi railed PSU and I just didn't know what they were, at all, nor what was its purpose. Now I know.
I'm pretty sure the brand is cheap af. What I don't know is how their PSU is built. It's a Golden Field ATX-600W. I've had an overlook of it on Google but didn't really find out anything that could let me know how it's built nor its specifications.

If its a "cheap af" unit, it needs to be replaced.

The MWE isnt a great unit either. Is the Seasonic S12 ii available where you are?

 

[LauroSalvatore]

Is the Seasonic S12 ii available where you are?

Nope it's not ):

My other 2 options are these:
https://www.coolermaster.com/catalo.../masterwatt-lite-600w-full-range/#image-Item8
https://cougargaming.com/products/psus/vtc/ (the 600watts one)

 

[NightHawkRMX]

As a rule of thumb, avoid any PSUs with lite in the name. You want a psu to be solid and reliable. Not lite.

The Cougar and Riotoro units would be more suited to a lower end gpu as they are extremely budget options.

I would say the MWE bronze is your best bet. While not great, its better than any of the other ones.

 

[LauroSalvatore]

I would say the MWE bronze is your best bet. While not great, its better than any of the other ones.

So... My GPU would run with that PSU? Because I asked the seller if it would work properly with a MSI GTX 670 Power Edition and he told me that that particular PSU isn't strong enough, implying that I need one with more watts.

Once again, my system has no fans (besides the CPU cooler, ofc) (open case), an Intel Pentium G4560, 1x8GB Corsair Vengeance LPX 2400Mhz, and only one HDD.

My motherboard is a Gigabyte H110M-H rev.1.0.

 

[NightHawkRMX]

Watts are fine. Quality is not.

You really need something better to power a 670 as it is a highly inefficient kepler card. While it likely will work fine if there are no other alternatives, its not ideal.

 

[LauroSalvatore]

Watts are fine. Quality is not.

You really need something better to power a 670 as it is a highly inefficient kepler card.

Well, that's what I can afford at the moment.

 

[NightHawkRMX]

If its the best you can afford, it's your best bet.
It likely will work fine if there are no other alternatives.

 

[LauroSalvatore]

If its the best you can afford, it's your best bet.
It likely will work fine if there are no other alternatives.

Okay, what's your recommendation on a good PSU for that GPU? The cheapest one you can think of when it comes to what you think could be optimal.

 

[NightHawkRMX]

A few decent cheap ones.

Corsair CX 550
EVGA BR600
Seasonic S12ii 620w
Seasonic FOCUS Plus Gold 550 (only $51rn)
EVGA BQ650w

 

[LauroSalvatore]

Seasonic FOCUS Plus Gold 550 (only $51rn)

Where is it at 51?

 

[NightHawkRMX]

Well, nevermind. It is $51 after rebate at NewEgg. I bet if you arent in the US you cant do the rebate.
https://www.newegg.com/seasonic-foc...&ranSiteID=8BacdVP0GFs-89BP7lrFRAyF5glPrT3a4A

 

[LauroSalvatore]

A few decent cheap ones.

Corsair CX 550
EVGA BR600
Seasonic S12ii 620w
Seasonic FOCUS Plus Gold 550 (only $51rn)
EVGA BQ650w

And my last question... Between the EVGA BR600 and the Seasonic S12ii 620w, which one would you recommend I buy?

 

[NightHawkRMX]

Well, the s12ii is older, but tried and true.

The BR is newer and doesnt have hiccups with sleep states on intel rigs. These can be disabled anyhow with no performance loss.

Edit: After seeing that the BR uses sleeve bearings and non-japanese caps, I now thing the s12ii is a better unit. Only buy the br600 if its a lot cheaper.