Power supply CPU connectors

[Bfuqua]

I'm sure this has been asked a dozen times or more, but I've looked and looked and can't find a straight answer to my exact question. 

 

I have a motherboard (MSI mpg x570 gaming plus) that has a 8+4 CPU power connector.

 

But my power supply (EVGA 850 B3)only has the 8 pin connector dedicated for CPU. The rest are either "VGA"(which I assume simply means graphics) or SATA. 

 

I know the extra 4 pin is largely unnecessary, but I'd like to plug it in anyway. But as I said, my power supply doesn't have an extra 4 pins for CPU. 

 

So would it be safe to use one of the other connectors? Or do they not deliver the proper power for CPU use? 

[Enderman]

No the PCIe power connectors are not the same asthe CPU EPS power connectors.

You'll fry your motherboard.

[Whiro]

5 minutes ago, Bfuqua said:

I'm sure this has been asked a dozen times or more, but I've looked and looked and can't find a straight answer to my exact question. 

 

I have a motherboard (MSI mpg x570 gaming plus) that has a 8+4 CPU power connector.

 

But my power supply (EVGA 850 B3)only has the 8 pin connector dedicated for CPU. The rest are either "VGA"(which I assume simply means graphics) or SATA. 

 

I know the extra 4 pin is largely unnecessary, but I'd like to plug it in anyway. But as I said, my power supply doesn't have an extra 4 pins for CPU. 

 

So would it be safe to use one of the other connectors? Or do they not deliver the proper power for CPU use? 

No you definitely don’t need it and don’t want it. 8pin is more than enough if you don’t plan to extreme overclocking ( I’m talking about ln2 oc) 

[Enderman]

7 minutes ago, Whiro said:

No you definitely don’t need it and don’t want it. 8pin is more than enough if you don’t plan to extreme overclocking ( I’m talking about ln2 oc) 

Some boards won't boot without the second 4/8 pin plugged in btw.

[Whiro]

1 minute ago, Enderman said:

Some boards won't boot without the second 4/8 pin plugged in btw.

First time I heard about it , do you have any examples of the boards? Just curious tbh

[Enderman]

5 minutes ago, Whiro said:

First time I heard about it , do you have any examples of the boards? Just curious tbh

Nah can't remember, it was years ago I saw the posts here.

Most modern motherboards work fine with only one.

[GDRRiley]

8 minutes ago, Whiro said:

First time I heard about it , do you have any examples of the boards? Just curious tbh

usual dual socket

[Spotty]

7 minutes ago, Whiro said:

First time I heard about it , do you have any examples of the boards? Just curious tbh

Dual socket boards, definitely. For any high end HEDT platforms if they have multiple EPS12V sockets then I would recommend using both even if it isn't required for it to boot.

For X570 as far as I know they will all work with just the 8pin. I haven't heard of any issues with not using the extra 4pin on any boards and I imagine that would be something that would have come up on the forums by now if it was an issue.

[Jurrunio]

If you cut a PCIe power connector (the ones marked "VGA") and make sure it has 2 12V wires and 2 ground wires in the right place I dont see why you can't use it, but this itself generates greater risk than just leaving the 4pin unused.

[Kisai]

43 minutes ago, Bfuqua said:

I'm sure this has been asked a dozen times or more, but I've looked and looked and can't find a straight answer to my exact question. 

 

I have a motherboard (MSI mpg x570 gaming plus) that has a 8+4 CPU power connector.

 

But my power supply (EVGA 850 B3)only has the 8 pin connector dedicated for CPU. The rest are either "VGA"(which I assume simply means graphics) or SATA. 

 

I know the extra 4 pin is largely unnecessary, but I'd like to plug it in anyway. But as I said, my power supply doesn't have an extra 4 pins for CPU. 

 

So would it be safe to use one of the other connectors? Or do they not deliver the proper power for CPU use? 

I'll echo others here and say you probably are fine. You'd have to invest in another power supply to get the necessary connector, and you might only find that in a higher wattage rating PSU. 

 

In general, you should always connect power leads for things that have them, and omit them them from devices without it. For example, some GPU's have one 6 pin, one 8pin or a 8+6, and thus you really should have both connectors, but this is because of the Tier of GPU. Now if the CPU you are using on the motherboard is a high TDP CPU, then yes, maybe you should have a higher rated PSU with the necessary connector.

 

But also look at the manual.

The PSU states:

EPS (CPU)

1x 8pin (4+4)

 

 

Then the Manual states:

If you look on Page 44, there is a reference to what is necessary:

Quote

1. Connect power supply to CPU_PWR1 and ATX_PWR1. (No other components are necessary but power supply.)

This is, of course, for flashing the firmware using the flash button. But this also tells me that ATX_PWR2 is considered optional to boot.

 

Now if you look on THIS forum and many forums going back to 2002, you will see the same advice over and over again "20 pin required, 4 pin optional", "20 pin+4pin required" , "24pin atx +4pin", "24pin+8pin", "24pin+8pin+4pin", "24+8pin+8pin" So we really are at a point where the existing ATX power standard simply doesn't work anymore, despite almost nothing changing with PSU's. So Intel released a new standard last year(2019) called ATX12VO.

 

https://www.intel.com/content/www/us/en/products/docs/devices-systems/desktops/single-rail-power-supply-platform-atx12vo-design-guide.html

 

This also essentially standardizes the modular cabling found on the PSU's. Of note the 24pin is replaced with a 10-pin, and the 4pin+8pin CPU still exist for higher TDP CPU's, plus a Molex connector with only the 12V power connected for motherboard cooling peripherals.

 

So you need to connect the power connectors dependent on the CPU you intend to use, and if you intend to overclock it still.

 

So as per the previous table, the 8pin connector is good for all CPU's from 24 to 32A, That's the 65 and 95w TDP CPU's. If you're going to pull 40A with a 165w TDP CPU OR, you're going to overclock a CPU up to 165w TDP, then you'll need that extra 4-pin to get there.

 

There is no way to simply connect a PCIe/Peripheral connector to the motherboard to get that extra power, even if you were technically able to connect it.