Question Power Supply connection.

Mar 18, 2019
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Long story short , power supply in old PC died ( Brown smells ) Purchased new PSU, (Civis brand- 700 Watt) Worked fine.
Old PC is very old needs replacing.
Planning to use newly purchased PSU as part of new PC build.
New motherboard is an Asus Rog Strix X470 I gaming ITX.
Motherboard has standard 24 pin and 8 pin EATX.

My power supply has one 24 pin and one 6 pin and one 4 pin 12 V EATX.
Problem, there is no 8 pin 12 V EATX
I'm thinking I will trim the 6 pin connector down to just 4 pins and use it with the other 4 pin connector to fit into the 8 pin motherboard connector.
The cables are the standard yellow + and black - and all seem to come from the one point inside the PSU circuit card.
The PSU is rated at 700 W and my total build is rated 340 Watt.
Do you see any problems doing this. ?

Strange thing, on opening my PSU I found a gadget.
It appears to be a small transformer about a 1 inch square cube attached to the removable cover.
Not connected to anything and positioned over a blank area of the circuit card over which it is located. Wish I could post a photo of it here. Absolutely no writing , part number or anything on it,
Any ideas,,

Looking forward to all comments , Thanks. Tom
 

justin.m.beauvais

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Dec 15, 2017
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I wouldn't modify a power supply if you can get away with it. Most motherboards with 8 pin CPU power headers are actually 8 or 4 pin compatible. Consult your motherboard manual, chances are it will tell you how to connect the 4 pin. Don't use the PCI-E connector as they might not be pinned out the same way. You might blow up the motherboard or CPU.

Why are you opening the PSU? When it comes to bad ideas when working on PC's opening the power supply is right near the top of the list... right up there with using toothpaste as a thermal compound. From the sounds of it you've found a ferrite core, or in normal terms, a magnet. They are put in place to help filter out line noise and interference.
 

Math Geek

Glorious
Herald
8-pin pcie and 8-pin cpu connections are not the same and can not be interchanged. they don't even fit into each other's connections for a reason. trying to do this is a one way trip to ruining some new parts.

don't know anything about your psu but at 700w it should have the needed connections. this tells me the psu is probably not the best quality and likely should be replaced with the rest of the system. get one from a quality company and you'll have all the power you need in a much less powerful unit.

you can post the model number here and possibly a pic of the label on the side of it and can look into it further but i'm pretty sure i know what i'll already find. been doing this long enough and seen enough low quality units to know what to expect based on the connections present.
 
Mar 18, 2019
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Kind thanks for your swift reply.

I have read that some people suggest using just one 4 pin of the 8, leaving the other 4 pins empty.
Some say to use just the right hand end 4 pins.
Some say this does not work. Seems to be a bit of uncertainty here.
I have read the the extra 4 pins will give the Motherboard more available power if required , without overloading just one 4 pin supply.
The manual says " Do not forget to connect the 8 Pin EATX 12 V Power Plug , Otherwise the system will not boot. Unfortunately there is nothing referring to using only 4 of the 8 pins or otherwise.

Yes , you are perfectly correct, " do not open a PSU, " primarily as there is high voltage inside , however I'm an electrician and aware of safety concerns. But thanks for your reminder. :)
I will be building my new rig into a very small case and I plan to remove the PSU cover and expose the circuitry inside my pc case. There is not much inside that large PSU case. My PC case is just 12 inch square and just enough room for MB, PSU ,and a GPU.
Cooling will be a challenge, however I plan enough fans to cool everything.
Ps I already checked the " gadget" it has no residual magnetism, However it could be inducted into it somehow, it is a good suggestion from you, thanks, I guess i will allow for it in my case.
So back to the 8 pin connector,, ??? i'M still unsure to connect all 8 or not.

any more suggestions please.
PPs I may be an electrician, but I'm certainly not a PC expert.
Thanks
 
Mar 18, 2019
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Hi math Geek, thanks for your reply,
I got the right type of connector for the CPU , just not 8 pin, the psu has plenty molex type connectors for drives and PCIe etc, just missing an 8 pin power.

I tried to find how to post a picture of my PSU but couldnt get it to work ,( Insert image ) but it kept asking for Http/ .........

could you guide me how to post a pic please.

Thanks so much, tom


you can post the model number here and possibly a pic of the label on the side of it and can look into it further but i'm pretty sure i know what i'll already find. been doing this long enough and seen enough low quality units to know what to expect based on the connections present.
[/QUOTE]
 
Mar 18, 2019
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Hi again math Geek,
Everything I read about PSU's refers to either 8 or 4 pin,, I have not found anything about a PSU having one 6 pin and one 4 pin,,
My PSU is CCCccRRRaaaaZZZZYYyYYY
 

justin.m.beauvais

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Dec 15, 2017
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Is this power supply a standard ATX one or is it a smaller form factor? They have some pretty nice SFF modular power supplies under the SFX standard. They are a good deal smaller than ATX and might work out better.

Some pictures of your power supply would help a lot as well. It'd at least give us a bit more to go on. It might be possible to rig up a connection but stability of the power would be questionable. CPU power needs to be cleaner than most other lines in the PC, so splicing together a connector might draw from less filtered circuits and impact stability, and possibly damage the system. If we were testing on an old system it might be worth a shot... but killing brand new hardware is not something I want to be in any way responsible for.
 

justin.m.beauvais

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Dec 15, 2017
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Well, the picture worked... that IS a cheap PSU. The picture isn't super helpful though.

HOWEVER, I've done some searching and they have 8 pin adapters.
https://www.amazon.com/Detachable-EPS-12V-Converter-Adapter-Sleeves/dp/B00Z04IY7M/ref=sr_1_3?crid=2D1SDZ6ZBI52H&keywords=8+pin+cpu+power+adapter&qid=1552925037&s=gateway&sprefix=8+pin+cpu+po,aps,163&sr=8-3
So, for $10 you don't have to pull a mad scientist and turn the machine into more of a fire hazard than it needs to be.

Hopefully that helps.
 

Math Geek

Glorious
Herald
an 8-pin EPS connection is rated for 235w from what i have read.

a 4-pin molex is not even close to that amount. that's asking for trouble using an adapter like that. if i recall right, a molex is around 50w available but it might be slightly higher. but it's nowhere close to 235w for the EPS. hooking a molex up to a connection that might ask for multiple times available power is asking for trouble.

if this was an experiment or other play project it might be fun to see what happens. but for your daily driver that you actually need, i'd not risk whatever might happen if you used such an adapter.
 

justin.m.beauvais

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Dec 15, 2017
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an 8-pin EPS connection is rated for 235w from what i have read.

a 4-pin molex is not even close to that amount. that's asking for trouble using an adapter like that. if i recall right, a molex is around 50w available but it might be slightly higher. but it's nowhere close to 235w for the EPS. hooking a molex up to a connection that might ask for multiple times available power is asking for trouble.

if this was an experiment or other play project it might be fun to see what happens. but for your daily driver that you actually need, i'd not risk whatever might happen if you used such an adapter.
It all depends on what he is using for a CPU. It might not need anywhere near that kind of power.

So, what hardware are you trying to build with? I know you mentioned that this is for a small form factor build, but are we talking a Ryzen 5 2400G or a more powerful CPU with a discreet GPU?
 
Mar 18, 2019
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Thanks for all your hely guys, my system will be ;

Asus Rog Strix X470 I Gaming Mobo
Ryzen 5 2600x cpu
2 x 8 Gb Corsair Vengence DDR4 3200 Ram
2 x Crucial P1 500Gb M.2 NVMe 2280 SSD
Asus Ge Force GTX 1660 6G Phoenix vid card

and my illustrious PSU.

according to Partpicker a total of 249 watt.
Before posting here at Tom's, i have read other blogs on the subject of using 4 pins or a 4 to 8 pin adapter, there doesn't seem to be an agreed consensus as to which way to go. I am open for ideas. perhaps a new PSU and make sure it has two 4 pin connect. My old PSU had only one 4 pin connector, so it would not have fitted my new system. How many 4P?
 
Mar 18, 2019
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Finnally found a description and picture of a 6 pin connector, the website says it is for PCIe,, if that
is so then it is of no use to me. I guess I just buy new PSU.
 

justin.m.beauvais

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Dec 15, 2017
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Yeah, I'm now on the side of getting a new PSU. Molex isn't going to power the 2600X. You simply lack the number of connections you need. If you hack up the PCI-E connector you won't have anything to power the GPU. So, check out the SFX form factor PSUs. You should be able to fit them into that enclosure with their casing intact as well.
 
Mar 18, 2019
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Thanks Everyone,
I just updated my parts order for a new Silverstone SFX modular 450 Watt 80+gold psu, i checked , and it comes with 2 x 4 pin connectors for the cpu power supply, I will plug in both sets. A good outcome, and hopefully I can leave the psu circuit card in it's little box, ;-) One day soon I hope to post my completed build, but I have a lot of work to do first. Watch out for a pc in a box , hahahah
Best wishes to all , Tom
 

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