modular cables not all the same!

FatRakoon

FatRakoon

FatRakoon

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Ah, I have had simlar issues in the past, but, I got a handful of Modular PSUs in my PCs.

Now, this PC here, that I am playing with right now, has an XPREDATOR 1000GM PSU and annoyingly, I have lost a load of its cables.

You know when its been in one PC for so long and you thought you wont need those cables anymore... Yeah, well now I do!

So, the PSU has sone BLACK connectors and some RED ones.

Now, thankfully the black ones are compatible with some of the other cables from other PSUs and I am using two of those to power up 2 HDs. I am also using ONE RED cable in a RED port as it has 2x6 pin PCIE power connectors on the other end, that has been powering an old nVidia 970 just fine.

Now, I have just bought an ATI card and I want to plop that in, instead of the nVidia. It does however have the 8 pin power socket and not the 2x6 Pin.

What I did do, was look through some of my modular cables, and I got one from a CORSAIR bunch ( I got a whole bad but I cannot find them ) but this was in the box of an old 850w and I had a fettle, and it does NOT fit into the BLACK ports in the PSU however id did fit lovely into a RED one!

So, I thought... hmm... Maybe?

But no.

Thankfully, the PC simply would not power up.. I gopt a quick flicker of lights and then off.

I have for the moment, put the orignal 2x6 cable into the RED port asd it does go into the 8 pin port with leaving out 2 pins.

I started the PC up and its been running now for a good few hours, I have removed all the nvidia gubbins and restarted it to help the system get in with the ATI in case it needed a restart and then I have played a few games and everything seems to be spot on.

The only one worrying thing that may or may not be something, is that even when I tried to load it up hard, none of the fans on the card came on. Small detail, but a detail.

So, is it fine using just the 6 instead of the 8?

I am assuming that its kind of like the AT 20 v 24 pin thing, plus also, I have actually seen a lot of card that have 6 pins, and yet there is solder across them.

I have a million questions, but the memory of a GoldFish!

Well, I remember having a Goldfish - it was a good memory!
 
Don’t mix cables from different brands. They don’t all use the same pin out and you could be asking for trouble.

If a GPU has an 8 pin PCIE connection then I don’t think you can get away with only using a 6 pin…
 
FatRakoon said:
So, is it fine using just the 6 instead of the 8?
Click to expand...
I wouldn't recommend it. If the card has an 8-pin instead of a 6-pin, it is because of the assumed power draw.

I'd also echo the above comment, mixing modular cables is a very bad idea because the pinout is not the same.
 
Ah, ok, well I am now on about 10 hours of use with it and I have just done a check up...

On pin 5 on the 6 pin connector, and indeed pin 6 on the 8 pin connector... These are SENSE A.
On the 8 pin connector pin 8 is GROUND and pin 4 is SENSE B

Ok, this is what I read... This is CUT & PASTE so its not my words.
>>>>>
The 6 pin PCIe power connector comes in a 6.25A (75W) version and a 12.5A (150W) version. The 6.25A version only requires that two 12V power connections be present, and only two ground connections need to carry current. The 3rd middle ground connection can be used to sense that the connection is plugged in. The 12.5A version uses 3 12V power wires and 3 ground wires to carry current. An additional two groundable sense connections can be added to the side to tell the PCIe device that a 12.5A compliant power connector has been inserted. Many power supplies that are 12.5A compliant have an additional 2 pin ground connector on the side of the 6 pin connector that can be used to make it to an 8 pin connector.

If a 12.5A 6-pin connector on an older power supply is connected to a newer 8-pin PCIe device, the PCIe device should not turn on because it doesn't know if a 12.5A compliant connection has been used. If all 6 wires are present on the 6 pin connector and the power supply can handle the current, then it is safe to get an adapter that will convert the 6 pin connector in to an 8 pin connector simply by grounding the two additional connections on the 8 pin connector.

The 2 sense connections on a 8 pin PCIe board could be permanently connected to the 6 pin ground connections with a little bit of solder and wire. This would convert it in to a 6 pin connection. Just be careful to not use any 6 pin PCIe power connectors that only have 2 12V wires, and thin wires that are smaller than AWG 20. If one fails to connect, all the current will go through the remaining wire and it could melt. If this is bad advice, then online sellers that sell Molex to 8 pin PCIe adapters should stop selling those first. That could easily end up runing everything through one wire.

>>>>>>

So yeah, while I have been lucky enough to get his running as it is, I definitely do need to find one of the proper 8 pin cables that is compatible.

Either that, or I will have to swap the PSU qith one of the others... I only have a few PCs with powerful PSUs though! I think however 1000w is probably overkill for this PC so I might get away with one of the 750 or 850 ones? IF they have an 8 pin connector that is!


Thanks guys.
 
You are extremely lucky that you haven't blown something up. Never ever use cables from one psu in another unless it's exactly the same model. There are many different OEM's that build psu's and they all have different pinouts, even some from the same manufacturer so a cable that works in one psu may fry something in another. The only cables you can safely use with different psu's are extensions.
 
Yeah, I know, I know...
This is why I have gone back to the 6 pin for the time being.

I have dug out an ood AMD A10 ITX Setup and thats NOT modular, however it does have a pair of 6+2 PCIE Connectors and as it only needs a few power connectors, this Modular XPREDATOR would go just fine in that.

But yeah, I am such an idiot, but I did look where the wires were going and they did look ok-ish

But the Sensor obviously made the PC fail to boot when I used the other cable.
 
This was a definite risk and you were very lucky. I recently had to change PSUs, as a faulty GPU burned out my old one. I was definitely tempted to use the old modular cables and save myself several hours of tedious cable management, but ultimately decided to do things the right way. If you've lost the cables and can't get new ones from the manufacturer, it's probably best if you get a new PSU. You could try repinning them, but then you have to be very, very, very careful with what they're rated to carry. Plus, any issues with pins not being seated correctly could cause you a major headache. There are some pretty decent affordable PSUs out right now, it might be worth a perusal to check if it won't just be easier to replace the entire unit.
 
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