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what da molex!

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  • Connection
  • Graphics
  • Graphics Cards
  • MSI
  • psu
Last response: in Graphics & Displays
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April 16, 2014 11:35:06 PM

My graphics card (msi r9 270x) requires 2 6 pin pcie connectors from the psu, my psu only has one and the graphics card came with a molex to 6 pin connector. i know it is a dumb question but do i need to connect both and can it be so that my graphics card shares connections with my fan
Thanks in advanced

More about : molex

a c 98 U Graphics card
April 16, 2014 11:47:27 PM

It's not so much a dumb question as a logic question. if it needs 2 molex connectors to fill that second 6 pin pci power slot, you would want to make sure of a few things first

1. that the molex are coming out of a 12v rail of your psu and that the psu is good enough to even power the 270x in the first place (requires 24 amps on the 12v rail generally) which will be listed on the side back or bottom of your psu
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a b U Graphics card
April 16, 2014 11:49:13 PM

Yes, you definitely need to connect both.
The most important question is: What's the make and model of your PSU?
If the PSU is up to it then there is no problem using a molex to 6 pin connector, and even daisy chaining the connectors to a fan.
If, however, the PSU is not up to it (and is poorly made), you are running a high chance of blowing up the PSU and anything/everything it's connected to (including your new video card.
Be careful!
What's the PSU make and model?
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a b U Graphics card
April 16, 2014 11:49:23 PM

MOLEX are always 12volt .

Yes your card needs both pci-e power connectors and one will be via the adapter from a molex
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April 16, 2014 11:57:54 PM

Brantyn Gerik said:
It's not so much a dumb question as a logic question. if it needs 2 molex connectors to fill that second 6 pin pci power slot, you would want to make sure of a few things first

1. that the molex are coming out of a 12v rail of your psu and that the psu is good enough to even power the 270x in the first place (requires 24 amps on the 12v rail generally) which will be listed on the side back or bottom of your psu


rhysiam said:
Yes, you definitely need to connect both.
The most important question is: What's the make and model of your PSU?
If the PSU is up to it then there is no problem using a molex to 6 pin connector, and even daisy chaining the connectors to a fan.
If, however, the PSU is not up to it (and is poorly made), you are running a high chance of blowing up the PSU and anything/everything it's connected to (including your new video card.
Be careful!
What's the PSU make and model?


my psu is a CiT 600W 12cm Silent Fan Dual Rail Power Supply - Black Edition
another question if i put a 3 pin molex into a 4 pin molex would it matter
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a c 98 U Graphics card
April 16, 2014 11:59:41 PM

yes...you would be missing part of the power delivery
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a c 98 U Graphics card
April 17, 2014 12:00:09 AM

again, not a stupid question because it's better to ask than to not ask and find out later.
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April 17, 2014 12:02:12 AM

Brantyn Gerik said:
yes...you would be missing part of the power delivery


Thanks man
i think i understand now.
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a b U Graphics card
April 17, 2014 12:37:31 AM

OK, I can't find any trustworthy reviews of that PSU.
It's listed on scan.co.uk here: http://www.scan.co.uk/products/600w-cit-black-edition-1...

It has 2x12V rails, each max 18A, so it can actually only provide 432W at 12V. In theory that would be enough (as long as you made sure that the PCIe connectors were attached to separate rails), but it has no 80 Plus classification, so you have no guarantee that it can actually provide it's rated wattage.

Someone who knows more may be able to identify the manufacturer and provide some more info. But I would be extremely nervous about powering a 270X from that. In theory it's within specs, but you have no guarantee it'll provide it's rated power (there are plenty that don't).
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a c 100 U Graphics card
April 17, 2014 12:55:31 AM

I must say 36 watts on a 600w is very suspicious
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a c 98 U Graphics card
April 17, 2014 8:55:10 AM

The psu is low quality, but there are definately worse out there. It should be more than enough to power a single 270x, but no more. It is very important to make sure it is plugged into the seperate 12v rails.

as far as being able to output 600 watts, it is unlikely. 80 plus certification is nice, but not a deal breaker for budget power supplies, as all it really is is an efficiency rating. There are tonnes of falsified 80 plus ratings, and i'd rather have no 80 plus than a false one.
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a b U Graphics card
April 17, 2014 9:41:46 AM

Brantyn Gerik said:
The psu is low quality, but there are definately worse out there. It should be more than enough to power a single 270x, but no more. It is very important to make sure it is plugged into the seperate 12v rails.

as far as being able to output 600 watts, it is unlikely. 80 plus certification is nice, but not a deal breaker for budget power supplies, as all it really is is an efficiency rating. There are tonnes of falsified 80 plus ratings, and i'd rather have no 80 plus than a false one.


Graphics cards shouldn't be run on a low quality PSU, it makes them run hotter, and shortens their life.
As some mods here say, those are not PSU's; but PSU shaped objects.
rhysiam said:

It has 2x12V rails, each max 18A, so it can actually only provide 432W at 12V. In theory that would be enough (as long as you made sure that the PCIe connectors were attached to separate rails), but it has no 80 Plus classification, so you have no guarantee that it can actually provide it's rated wattage.


How do you know that power supply has 432W on the +12V rail? However, I do know it doesn't.

80 PLUS certification doesn't signify whether the power supply can deliver its rated wattage, only whether the efficiency of the power supply is above a certain percentage at a given load.
Brantyn Gerik said:
80 plus certification is nice, but not a deal breaker for budget power supplies, as all it really is is an efficiency rating. There are tonnes of falsified 80 plus ratings, and i'd rather have no 80 plus than a false one.


Please don't say such things.
Just because the world is filled with crap PSU's doesn't mean we should say using a crap PSU is okay.
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a c 98 U Graphics card
April 17, 2014 9:49:43 AM

They should not be run on low quality psu's, but in this case it will work, were it a higher power draw gpu there would be more of a problem, but as it stands, OP won't have a problem as long as he corrects it in the right way. We would all suggest an upgrade, but until such a time, he will be fine with what he has.

The calculation for power output on the 12 rails (plural) is correct for what the power supply says it is rated for. of course this is likely a peak value, and the sustained wattage is much lower, but it should still be more than enough for a 270x
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a c 98 U Graphics card
April 17, 2014 9:52:23 AM

this is not a thread about psu quality, it is helping OP get his system working. it WILL work with that psu, and it will not cause problems if connected correctly.

It's not a great power supply, but he has it and he wants to get his system up and running so there is nothing we can do about it. i'm not going to go out and tell him not to use a product that will work for his intended use. I can suggest that he upgrade soon, but otherwise we have told OP what he needs to know to get his system running
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a b U Graphics card
April 17, 2014 10:11:18 AM

Brantyn Gerik said:

The calculation for power output on the 12 rails (plural) is correct for what the power supply says it is rated for. of course this is likely a peak value, and the sustained wattage is much lower, but it should still be more than enough for a 270x


You do know how multirail PSU's work, right? 18A on first + 18A on second is not equal to 36A total; it's lower than that. I usually assume it's 80%.

so the correct +12V rating for that power supply is around 28 A or 336W. I don't think it's wise to run a 270x on a 336 W power supply; as the card itself is around 180W TDP.

Since the power supply has only one 6 pin connector, we don't know if the molex connectors are connected to the same rail as the PCI-E or the other; and which rail the CPU runs off of. If the power supply came with 2 connectors, it's not a problem as they design it appropriately. The current on any single rail shouldn't exceed 18A.
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a b U Graphics card
April 17, 2014 8:42:17 PM

@CST1992 - "How do you know that power supply has 432W on the +12V rail? However, I do know it doesn't. 80 PLUS certification doesn't signify whether the power supply can deliver its rated wattage, only whether the efficiency of the power supply is above a certain percentage at a given load."

How do I know? Well, if you look at the link I provided in my post above, (http://www.scan.co.uk/products/600w-cit-black-edition-1...), scan.co.uk list the max combined 12V output at 36A. Of course, we're trusting the listed specs. If you somehow know that it doesn't it might be an idea to post some evidence or justification?

RE 80 Plus - I am well aware that it is a measure of efficiency. However, one of the tests is to measure the efficiency at 100% load. To gain an 80Plus certification a PSU needs to be able to supply it's rated load, at least for the duration of the test. It's no guarantee of quality, but at least you have some evidence that the PSU can approach its rated load. It's better than nothing that's for sure!

RE OP's question, the way I would put it is that powering that GPU of that PSU increases the risk of problems significantly. Clearly @Brantyn Gerik is happy with the level of risk and @cst1992 isn't. It's really up to the OP whether that's a risk she/he is willing to take that risk.

If it was me, I'd be saving the extra $50 or so for a Corsair CX430 or similar.
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a b U Graphics card
April 18, 2014 12:22:01 AM

Please use 'Reply' feature from bottom right or quotes by using <Ctrl> - Q or [quote ] [/quote] tags. Takes more time, but separates by colors, so cleaner and easier to read.
Quote:
Of course, we're trusting the listed specs. If you somehow know that it doesn't it might be an idea to post some evidence or justification?

Here's a thread that's your evidence:
http://www.tomshardware.com/forum/306437-28-single-rail...

You can find this thread under the following : Components Forum -> Power Supply Guides and UPS info

If you ask me, I'd not trust those specs. Per-rail? Maybe, but combined, absolutely not.
Quote:
To gain an 80Plus certification a PSU needs to be able to supply it's rated load, at least for the duration of the test. It's no guarantee of quality, but at least you have some evidence that the PSU can approach its rated load. It's better than nothing that's for sure!

I'd say you're right, the power supply can reach 100% load if a certification is given but that is not the measure for quality; what noise and ripple values the power supply gives out on the various rails and what protections it has provides measure of quality.
Quote:
OP's question, the way I would put it is that powering that GPU of that PSU increases the risk of problems significantly. Clearly @Brantyn Gerik is happy with the level of risk and @cst1992 isn't. It's really up to the OP whether that's a risk she/he is willing to take that risk.

I'm pretty sure the max current provided by the +12V rails is somewhere around 28 A and running a 180W card that's 15A for itself is dangerous, especially when we don't know which rail is providing how much current and what rail the CPU's running off of.
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