Question 6pin to 8 pin adapter

Aug 12, 2021
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Hey i just bought the xfr rx 6600xt it needs an 8 pin connector from the powersupply, however i only have a 6 pin from the psu.
would i be okay with an 6 pin to 8 pin adapter?
The psu is rated for 1100 watts with 90% efficiency so i should be okay on that front.
Link to the card: https://www.xfxforce.com/shop/xfx-speedster-qick-308-amd-radeon-tm-rx-6600-xt-black#2
Link to computer specs: https://www.workstation4u.de/media/pdf/2d/53/c1/Fujitsu_Celsius_R920-datasheet.pdf
with
Intel® Xeon® processor E5-2670
and 64Gigs of Ram
 

Jmi20

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Using an adapter is a bit controversial, but im pretty neutral when it comes to this so im not gonna tell you whether you should or shouldnt. Just some things to keep in mind.

based on my previous testing,

  • the weak link seems to usually be the connector itself, in the case of sata or molex to pcie.
  • even very thin wires tend not to get very warm.
  • some gpu manufacturers do include adapters in the box.
  • a lot of third party adapters are low quality.
  • typically, if a psu doesn’t have a pcie (in your case an 8 pin) connector; that means it wasn’t meant to handle it.
  • the only difference between 6 pin and an 8 pin pcie connectors are two extra ground wires.
it is up to you if it is worth the risk or not. Ive done it, but I won’t rely on it…
 
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Wolfshadw

Titan
Moderator
This is a workstation and not a home PC. The power supply was not designed for powering graphic cards. In any rate the 6-pin power from the power supply only provides up to 75 watts of power (in a typical power supply). The graphics card you have requires up to 150 watts of power (8-pin). Using an adapter isn't a good idea for two reasons:

  1. The power supply may not care how much power is pulled from the 6-pin cable. Overloading the cable could cause cable melt/card damage/fire.
  2. If the power supply limits the 6-pin cable to 75 watts, your system will likely lock/shut down whenever the card requires more than 75 watts from the 6-pin power cable.
My rule is that if the power supply does not have the required power cables for your graphics card, it needs to be replaced (and in your workstation, that may not be so easy).

-Wolf sends
 
Aug 12, 2021
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Using an adapter is a bit controversial, but im pretty neutral when it comes to this so im not gonna tell you whether you should or shouldnt. Just some things to keep in mind.

based on my previous testing,

  • the weak link seems to usually be the connector itself, in the case of sata or molex to pcie.
  • even very thin wires tend not to get very warm.
  • some gpu manufacturers do include adapters in the box.
  • a lot of third party adapters are low quality.
  • typically, if a psu doesn’t have a pcie (in your case an 8 pin) connector; that means it wasn’t meant to handle it.
  • the only difference between 6 pin and an 8 pin pcie connectors are two extra ground wires.
it is up to you if it is worth the risk or not. Ive done it, but I won’t rely on it…
Thanks for the reply, some good thoughts. if i do it, and do a stress test are there any other risks i should be on the lookout for, other than sytem shutdown and melting the wires connecting to the gpu?
 
Aug 12, 2021
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This is a workstation and not a home PC. The power supply was not designed for powering graphic cards. In any rate the 6-pin power from the power supply only provides up to 75 watts of power (in a typical power supply). The graphics card you have requires up to 150 watts of power (8-pin). Using an adapter isn't a good idea for two reasons:

  1. The power supply may not care how much power is pulled from the 6-pin cable. Overloading the cable could cause cable melt/card damage/fire.
  2. If the power supply limits the 6-pin cable to 75 watts, your system will likely lock/shut down whenever the card requires more than 75 watts from the 6-pin power cable.
My rule is that if the power supply does not have the required power cables for your graphics card, it needs to be replaced (and in your workstation, that may not be so easy).

-Wolf sends
Yeah it is a strange setup in many ways, however if you look at the tech spec i linked to, the same psu can be confgured to a amd firepro w8000 which has an tdp of 225 where as the amd has one of 160.

How much power is the card able to drav from the pcie slot? i'm just thinking about how big the gap is between what it needs and what i can get from a 6 pin
 
Aug 12, 2021
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then what adapter are you talking about? is the other end 6+2pin?
what the psu spec said the pcie out is?
the other end is a 6 pin, but i would connect it to a 6-8 pin cable

The Psu is a bit strange, it has a 6 pin female socket which is from where i power my current gpu with a double male 6 pin
 

Jmi20

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I borrowed this image from a post in another forum, might help you more:


in the bottom left you would see a regular 6 pin. As the note says the official specs lists pin number two as no connection, but most psus have a 12 volt power wire there anyway.

on top is the 8 pin pcie power connector, the sense wires are just ground wires that tell the gpu if a connector is plugged.

theoretically, you could create a “true” 8 pin pcie connector by splicing two independent ground wires into the pcie adapter.

but as i said im neutral on this, im not telling you to do or not to do anything. Im just saying what could be done… beware the risks if you’re gonna go through with this.
 
Aug 12, 2021
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I borrowed this image from a post in another forum, might help you more:


in the bottom left you would see a regular 6 pin. As the note says the official specs lists pin number two as no connection, but most psus have a 12 volt power wire there anyway.

on top is the 8 pin pcie power connector, the sense wires are just ground wires that tell the gpu if a connector is plugged.

theoretically, you could create a “true” 8 pin pcie connector by splicing two independent ground wires into the pcie adapter.

but as i said im neutral on this, im not telling you to do or not to do anything. Im just saying what could be done… beware the risks if you’re gonna go through with this.
Thanks again, good help for someone with limited knowlegde on this subject.

I just took a look inside my computer specefically on the psu, and apparently it has sockects for 3, 6 pin cables i'm just only using one at the moment.
However this raises a new question, how would i go about plugging in one 8 pin to the gpu from the two or three 6 pins available?
 

Jmi20

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However this raises a new question, how would i go about plugging in one 8 pin to the gpu from the two or three 6 pins available?
the adapter…

a 6 pin to 8 pin adapter would have the two extra ground wires connected to two existing ones.

you could cut off those two extra ground wires and splice them into their own independent ground wires, creating the “true” 8 pin connector i said earlier. But you would have to cut off those two extra ground wires from another 6 pin or a sata/molex chain.

but please beware the risks when doing this, i cant confirm it’s long term impact to the psu or any other components.

Another thing, i think some gpus allow you to connect a 6 pin pcie instead of an 8 pin, the gpu would detect it and will operate in a lower power mode. But ive also never tried this either…
 
Aug 12, 2021
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Could i just use a 6+2
the adapter…

a 6 pin to 8 pin adapter would have the two extra ground wires connected to two existing ones.

you could cut off those two extra ground wires and splice them into their own independent ground wires, creating the “true” 8 pin connector i said earlier. But you would have to cut off those two extra ground wires from another 6 pin or a sata/molex chain.

but please beware the risks when doing this, i cant confirm it’s long term impact to the psu or any other components.

Another thing, i think some gpus allow you to connect a 6 pin pcie instead of an 8 pin, the gpu would detect it and will operate in a lower power mode. But ive also never tried this either…
I see, i don't quite trust my knowhow enough to do that i think. i would like to try to avoid making a frankenstein cable, mainly because i don't trust myself to be a very good surgeon hahah
Couldn't i just get a 6+2 cable and then plug the 2 into ground in the other socket on the psu or am misunderstanding how this works?
 

Jmi20

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The two extra ground wires are spliced into the existing ground wires, the only way to disconnect them is to cut it off…

I’ve only seen 6 pin to dual 8 pin adapters, but if you could find a dual 6 pin to single 8 pin then it would be better.
 

Jmi20

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The end of an adapter would look like this:


you see those two black wires that loop? You would have to cut them off and splice them into independent ground wires.

you could run it as is, none of the wires got dangerously hot in my testing. As i said, the weak link is usually the connectors themselves. I only mention splicing as an option…
 
Reactions: thereisnospoon4u
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The end of an adapter would look like this:


you see those two black wires that loop? You would have to cut them off and splice them into independent ground wires.

you could run it as is, none of the wires got dangerously hot in my testing. As i said, the weak link is usually the connectors themselves. I only mention splicing as an option…
i found this
https://www.ebay.com/itm/264971090972?_trkparms=ispr=1&hash=item3db181fc1c:g:6ogAAOSw8LNeFym5&amdata=enc:AQAGAAACoPYe5NmHp%2B2JMhMi7yxGiTJkPrKr5t53CooMSQt2orsStdebXPz4ZTXCT8FI9kPBh%2BpS%2FsonMgQ1IokqrQ1FsRKq8QoejLlu%2BPdAXyCen65D6QETy9FjUJPVbpa8dkcjdVTmpwvdYw2kvQpqlzVVAsyD19viHPrO8M%2FicqAagORdEm%2Bed12tGaMfeuRELdd2Ktm1nguh91jXmSTEdQRy%2Bt%2F2H%2BclpouFXNUqiKUAKdBulFA1yx1A1BH4GEYcNECEAoksHxmX5r%2BazzKgrTvWg6ukjnpSCGylGpNrcHbnFeemYIWuZQvzpsLKCSYjYVvAmjk1rD65U7amXF1WBv4c67yu7xKbPORc3yrKoNH3t4GsKuZIOffxtMNdDXxlqDyeHIgulq34X0RDcKWO4TuPxMt5r78F8o%2BPs6f1wRsZLVHGdsH%2B4wzhK7UCkqBzvBp%2BN%2FuyIzQLV644LJ7%2BfC%2FqJH7zDdNeVd5Vy8aI9NWyFNp0aaF4RyyoAckcWAtu7vNfeAdjI877HBN3c%2FQ2ACjhvBd3zO1oLYdwVN88KyBHpTWWr%2FbtoAqUZy4te4ZCiMqglyd5m0oVBnhP%2FmJHlwJDOWSVYmolF%2FmQRkhI%2FuhtlXtRzSKv3jr2W5Is7QMkkEDMNOR5qVyWJ16sEOxlV1dpyLsET7SvFz5fUIbOrn3MZyFKSxp7LWJiFHFFglVERiODgerIku888sWRAKVZOnbcXtHTXTpg36em2rQxJ2RePyuUD%2FmlUlYTld2JVSeFCpMyZsc7VvPffp%2B1jmzHAEnlqJp%2F%2FGsBpPhSk%2B8e%2FoS5Teb72VtklKvFKj4S1WkBw9DtyloCv4BdbNFKG2mRockHEsgj83H%2FpujbsftsLwLMmtzVHNp6ofe5y4zJvimLgx95EA%3D%3D|ampid:PL_CLK|clp:2334524

however shipping is going to take the better part of a month

i might just try to use the adapter untill it arrives
if it gets 75 watts from the motherboard slot and 75 from the 6 pin and its tdp is 160 then that's only 10 watts over, that doesn't sound completely unreasonable, does it?
also i wonder if it's possible to powerlimit the card through the BIOS?
 

Jmi20

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i might just try to use the adapter untill it arrives
if it gets 75 watts from the motherboard slot and 75 from the 6 pin and its tdp is 160 then that's only 10 watts over, that doesn't sound completely unreasonable, does it?
unfortunately, it doesn’t work that way. The gpu could draw more than it’s rated tdp.

An R9 390 for instance has a 275W tdp, but i frequently get peaks of more than 400 watts under heavy load measured through a wattmeter, not including cpu, mobo, ram, etc.

I don’t think you could bios mod the newer amd cards, but you could undervolt in windows through afterburner or wattman.

edit: but to be fair, it was overclocked to 1150 core, 1600 memory. And was running furmark. Real world conditions are typically lower.
 
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unfortunately, it doesn’t work that way. The gpu could draw more than it’s rated tdp.

An R9 390 for instance has a 275W tdp, but i frequently get peaks of more than 400 watts under heavy load measured through a wattmeter, not including cpu, mobo, ram, etc.

I don’t think you could bios mod the newer amd cards, but you could undervolt in windows through afterburner or wattman.

edit: but to be fair, it was overclocked to 1150 core, 1600 memory. And was running furmark. Real world conditions are typically lower.
I'll give it a go and see if it will boot and then run watt man to try and limit it until i get the 2 x6 - 8

Thanks for the help, much appreciated!
 
Aug 12, 2021
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unfortunately, it doesn’t work that way. The gpu could draw more than it’s rated tdp.

An R9 390 for instance has a 275W tdp, but i frequently get peaks of more than 400 watts under heavy load measured through a wattmeter, not including cpu, mobo, ram, etc.

I don’t think you could bios mod the newer amd cards, but you could undervolt in windows through afterburner or wattman.

edit: but to be fair, it was overclocked to 1150 core, 1600 memory. And was running furmark. Real world conditions are typically lower.
I have one final question though, when you talk about cutting two pins off and attatching them to the 6 pin i assume it is what is being done here:
View: https://www.youtube.com/watch?v=usDW9wjbLDg
correct? how is this different from just using an 6 to 8 pin adapter, and how does this allow 150W powerdraw instead of just 75, if there is still the same amount of wires connected to the psu?
 

Jmi20

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No problem, but please do remember, I couldn’t vouch for this being trouble free at all, you could potentially take out your gpu or worse, start a fire. I would honestly just use this as a temporary solution.

i see that the highest end gpu your workstation could be equipped with from the factory is the nvidia quadro 6000, which has a 6 pin and 8 pin pcie connector. Which means, the power supply from the top end model would natively support a gpu with an 8 pin.

surely you would be able to find a power supply from the top tier model online…
 
Aug 12, 2021
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No problem, but please do remember, I couldn’t vouch for this being trouble free at all, you could potentially take out your gpu or worse, start a fire. I would honestly just use this as a temporary solution.

i see that the highest end gpu your workstation could be equipped with from the factory is the nvidia quadro 6000, which has a 6 pin and 8 pin pcie connector. Which means, the power supply from the top end model would natively support a gpu with an 8 pin.

surely you would be able to find a power supply from the top tier model online…
As far as i can see and as far as i know, this is the top tier psu, it might have been connected via 2 x 6 -8 + another 6 pin, that would explain the three 6 pin sockets in the Psu.
 

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