4 pin vs 8 pin 12V plug on PSU

[travistee]

I have an PSU with a 4pin plug.

My mobo can take either 4 pin or 8 pin. It has a cover over the first 4 pins that can be removed if you have the 8 pin psu plug.

Is there any reason I should get a PSU with the 8 pin plug?

[Wizard]

Re: 4 pin vs 8 pin 12V plug on PSU

Recommended.

C2D cpus can exceed 65W and some models can go over that. Athlon high speed ones (above 2.6GHz often is 65 and some over 3.0GHz easily exceed 125W.

Cheers, Wizard

[travistee]

Re: 4 pin vs 8 pin 12V plug on PSU

Can you explain that in terms of what the limitations of the 4 pin plug are?

[jpdoe]

Re: 4 pin vs 8 pin 12V plug on PSU

In order to feed the CPU you need to move electrical current from the PSU to the motherboard. Each cable can conduct so much amperage. Cables have internal resistance. Connectors have contact resistance, and each time you unplug it and plug it again it tends to go up.
As the CPU power requirements increase, so does the current needed to feed it. So you need more motherboard power connectors to keep things under control.
Maybe you've heard horror stories where the PSU connector plastic melted and became a constant fixture of the motherboard? The reason is heat emitted by the metal plugs, that coudn't stand the amount of electric current running through them. A few connectors and cables more could have prevented that from happening.

The bottom line is: connectors are there for a reason. If you ignore them, you better understand the consequences. If you have a not so hungry CPU things will be OK. If you have a super duper quadcore that consumes 125W things will get toasty in a short time.

[PCBONEZ]

Re: 4 pin vs 8 pin 12V plug on PSU

The only difference between 4 pin and 8 pin is that 8 pin has more wires and more pins and so can handle more current.
-
The limitations are:
The current capacity of the wires.
The current capacity of the pins in the connectors.
The current capacity of the traces on the board.

When they want to more more amps than 4 pins or wires can move they add more wires and pins.

[Usually]
All the +12v in the 4 pin are connected together on the board.
- As are all the grounds.

[Usually]
All the +12v in the 8 pin are connected together on the board.
- As are all the grounds.

.

[stevo1210]

Re: 4 pin vs 8 pin 12V plug on PSU

I have an Asus P5K-E WIFI AP motherboard (the one in my sig) and I'm using a Thermaltake 430W TR2 PSU with a 4 pin +12V cable. Should I be concerned as well?

So far It's been running for nearly a year and I haven't experienced any issues yet and I think the connector is still OK from my routine checks last month.

Thanks.

[Wizard]

Re: 4 pin vs 8 pin 12V plug on PSU

D920 is 95W cpu, that is bit concerning with 4 pin plug. Best to find a solution to get 8 pin plug hooked up or get another PSU. Seasonic is good make and quieter.

Cheers, Wizard

[travistee]

Re: 4 pin vs 8 pin 12V plug on PSU

I used my D 820 in an Asus p5p800se for a few years until the mobo died.

My PSU only had the 4pin plug. I think at that time (2005), the PSUs all came with 4 pin 12V ( I think?).

I asked the question because I'm planning to upgrade to a quad core.

[Wizard]

Re: 4 pin vs 8 pin 12V plug on PSU

Which Quad? Lot of them tend to be 125W

Cheers, Wizard

[travistee]

Re: 4 pin vs 8 pin 12V plug on PSU

Q9300

[bgavin]

Re: 4 pin vs 8 pin 12V plug on PSU

I have seen recommendations against using only four pins of an ESP-12V mobo connector. It is possible they are using smaller land patterns on this board, expecting the load to be distributed across 8 pins.

One is probably safer to buy a 4-to-8 adapter. Use the 4-ping PSU connector, and the adapter to split those lines to all 8 mobo pins.

[PCBONEZ]

Re: 4 pin vs 8 pin 12V plug on PSU

Sometimes the 4-pin plugs will arc/burn in the contacts (pins) if they are pulling too much current.
Usually if there is a problem the pins are the weakest link.
So - If you are concerned then do something to get more pins in there to handle the current.

If you have 4-pin PSU and 8-pin MoBo then one of those adapters is at least some protection.
You might still burn/arc at the 4-pin end but it won't damage the connector on the Mobo too, just the one in the adapter.

.

[PCBONEZ]

Re: 4 pin vs 8 pin 12V plug on PSU

bgavin is correct.

If mobo manual specifies to not use a 4-pin then don't use one.
Traces on mobo may not be in common and may burn-out.

You can check with ohm meter or looking at the solder joints.
If all 12v and all grounds in the mobo 8-pin plug are in common then a 4-pin should be okay to use as far as the mobo goes. - If the pins can handle the current.

.

[jpdoe]

Re: 4 pin vs 8 pin 12V plug on PSU

Man... It sure is interesting to lurk in these forums.

[PCBONEZ]

Re: 4 pin vs 8 pin 12V plug on PSU

Traces on mobo may not be in common and may burn-out.

I have seen this (pins not in common) mostly on dual processor boards where 1/2 the 8-pins go to one CPU and the other 1/2 to the other CPU.

That doesn't mean they couldn't do something similar on a single CPU board though.

[stevo1210]

Re: 4 pin vs 8 pin 12V plug on PSU

I just read my Asus P5K-E manual and it says I can either use a 4 pin or an 8 pin 12V connector. If I want to use an 8 pin connector, I have to remove the plastic cap covering the 4 other pins. Does this still mean it's OK to use a 4 pin 12V connector?

Thanks.

[Wizard]

Re: 4 pin vs 8 pin 12V plug on PSU

I still say not ok especially iwth 95W cpus. Both cpus you have and the future Q9300 is 95W. Get new PSU especially if your is older. Seasonic with 120mm fan is quiet also you will get SATA connectors, PCI-E connectors for the video cards. And wirings are all sleeved. Which is nice.

Nix on 4 to 8 adapters.

I had few ATX connectors burn out. Big job to replace and leaves you with old stuff.

Cheers, Wizard

[bgavin]

Re: 4 pin vs 8 pin 12V plug on PSU

I have a 63w P4 going into service on an MSI board with ESP-12V 8-pin connectors. Embedded VGA, single disk. This is a minimal power draw for sure.

I agree with Wizard to avoid using adapters with high current loads. The 8-pin cabling inside the PSU is 8 wires all the way to the board, as it should be with high current.

There are places where Band-Aids are inappropriate and real stitches are required. In my case, my modest 350w PSU with 4-pin ATX12V, into an adapter or straight into the board (if mfgr allows) is a workable Band-Aid. I can't find either Yes or No in the manual, about using a 4-pin cable in the 8-pin jack.

[PCBONEZ]

Re: 4 pin vs 8 pin 12V plug on PSU

I just read my Asus P5K-E manual and it says I can either use a 4 pin or an 8 pin 12V connector. If I want to use an 8 pin connector, I have to remove the plastic cap covering the 4 other pins. Does this still mean it's OK to use a 4 pin 12V connector?
Thanks.

Yes it's okay.
That means the pins are in common.

Cap is just to keep junk out of unused socket.

[PCBONEZ]

Re: 4 pin vs 8 pin 12V plug on PSU

I still say not ok especially iwth 95W cpus. Both cpus you have and the future Q9300 is 95W. Get new PSU especially if your is older. Seasonic with 120mm fan is quiet also you will get SATA connectors, PCI-E connectors for the video cards. And wirings are all sleeved. Which is nice.

Nix on 4 to 8 adapters.

I had few ATX connectors burn out. Big job to replace and leaves you with old stuff.

Cheers, Wizard

Adapter w/8 pins at MoBo keeps you from burning the pins in the motherboard.

If pins burn it will be in the adapter to PSU connection.

- Easy to fix.
- No broke MoBo.
That was the point.

.