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Motherboard 4 pin EPS vs 8 pin EPS connector for power?

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March 21, 2013 7:32:47 PM

What are the differences in 4 pin EPS connectors vs 8 pin EPS connectors? I'm 14, and DEFINITELY not an electrician, but I know my way around computers. However, a recent customer wanted a powerful, but VERY compact computer. I was planning on building it on a micro ATX motherboard and an AMD FX-6300, BUT I was suddenly concerned about one thing- the CPU power connector. I've only built a Pentium micro ATX build before, and being power conservative, I figured I didn't have to worry about using a 4 pin. However, what is the limit that a 4 pin becomes too little? An i5? An AMD FX 6 core? I would like to know for future reference, as I like both the form factor and price of Micro ATX, but I am worried about CPU power consumption. I have heard some people on other forums take an AMD FX-8350 and overclock to 5 GHz easily on a 4 pin, but I don't feel that would be recommended. Is it typically safe to overclock on a small power source, or am I just being over exaggerational? I don't want to fry motherboards, but I certainly don't want to spend more for features I don't need. Also, what is the difference between TDP and max load power consumption? Thanks for any help!
a b V Motherboard
March 21, 2013 7:53:30 PM

If he wants compact you should be coping at ITX. Micro ATX is not that small.

If you are building it new there is NO reason to EVER get a PSU with 4 pin to run an 8 pin board. Or get a PSU with 4 pin at all. It's beyond silly.

Not sure what you mean by "overclock a PSU" but you can't. At all. You need to get a quality PSU for any build. PSU makers lie ALL the time. Toms has articles on this. And you ALWAYS want to be a hundred watts or more below the rating for efficiency reasons. And that's on a good one. On a bad one approaching the rating can destroy the PC or burn someones house down.

Lastly, there is no money to be made on home built PC's. That's a basic fact. That you say "customer" and your 14 is not a good idea. Friends and family... OK. But there are a whole lot of tax and liability issues with "customers". What are you going to do when the PC you built burns their house down and they Sue you?
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a c 168 V Motherboard
March 21, 2013 7:58:11 PM

Short answer: You only need 8 pins for very powerful processors. 4 pins is plenty for anything drawing under 150 watts.

Long answer: Be careful when you talk about 4 pin EPS connectors. There is a 4 pin EPS connector, but it is not synonymous with the 4 pin ATX connector. The 4 pin EPS connector is known as the 'tertiary' connector whereas the 8 pin EPS connector is known as the 'auxiliary' connector. The 4 pin ATX connector is known as the 'auxiliary' connector in the ATX specification. The 24 pin main connector is identical for both.

The tertiary 4 pin EPS connector is optional and will only be found on high end, high current power supplies. It's purpose is two fold. First, on high end motherboards and servers it works in tandem with the 8 pin EPS auxiliary connector for a total of 12 auxiliary pins. Second, on motherboards that are not EPS compliant, it can be substituted for the ATX12v 2.x 4 pin auxiliary connector. Since the 4 pin EPS tertiary connector is optional, not all EPS power supplies have it. Instead, many will split the 8 pin EPS auxiliary connector into two 4 pin connectors which allows it to be compatible with a motherboard that is only ATX compliant and thus features a single 4 pin auxiliary slot rather than an 8 pin auxiliary slot or an 8 pin auxiliary slot plus an optional 4 pin tertiary slot.

It is safe to overclock anything short of a SandyBridge-E with just a 4 pin connector, but I wouldn't try and win any competitions with it.
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a b V Motherboard
March 21, 2013 8:08:12 PM

8 pin is rated to safely deliver twice as much power as 4 pin for CPU power connectors, 288W versus 144W IIRC. There aren't any modern CPUs without significant overclocking where a 4 pin is not good enough, but it's also not difficult to find decent motherboards and PSUs that have 8 pins anyway.

The 4 and 8 pin connectors and sockets are inter-compatible. IE an 8 pin slot can have a 4 pin connector and an 8 pin connector can have half of its connectors plugged in and the other half not plugged in for a 4 pin slot. It is best to simply make sure that you have enough power for the CPU. If it uses say 130W or more, then it's best to use an 8 pin slot and an 8 pin connector. Any less for CPU power consumption and it doesn't really matter.

For example, where you mentioned the FX-8350 at 5GHz, you are right in that it is best to have an eight pin connector. However, no modern CPU needs an 8 pin connector and slot unless it is overclocked and many (especially Intel's Ivy Bridge CPUs) can still get safely away with a 4 pin even when highly overclocked.

The power supply needs to be matched for the job. For example, a system with an FX-6300 that doesn't have a huge overclock (maybe brought up to 4GHz or so) and a Radeon 7850 and otherwise low-power components such as a basic motherboard, storage, and such will be fine on an Antec VP-450W. However, as said above, some PSUs lie. For example, although Antec's VP-450, a 450W PSU, is enough, many 600W PSUs are not simply because wattage is not actually the important number, rather that would be +12V amperage, and many such PSUs lie about their power delivery anyway. Examples of such liars can include RAIDMAX, Logisys, and many more.

TDP is a term related to maximum heat generation and such, so it's only loosely related to power consumption. Maximum load power consumption is a little more difficult to quantify because even parts of the same model can have a little variance in their power consumption. TDP is also not necessarily even true. It's oftentimes greatly exaggerated for safety's sake and simplicity.

EDIT:
@unksol

I'll also say this to you: I make a very decent amount of money off of selling home-built computers. I have to sell a lot of them to make any serious profit, but it works, especially as a hobby that pays for itself. I wouldn't recommend that anyone try to make their whole living off of it, but there is money in it.
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March 21, 2013 9:51:03 PM

blazorthon said:
8 pin is rated to safely deliver twice as much power as 4 pin for CPU power connectors, 288W versus 144W IIRC. There aren't any modern CPUs without significant overclocking where a 4 pin is not good enough, but it's also not difficult to find decent motherboards and PSUs that have 8 pins anyway.

The 4 and 8 pin connectors and sockets are inter-compatible. IE an 8 pin slot can have a 4 pin connector and an 8 pin connector can have half of its connectors plugged in and the other half not plugged in for a 4 pin slot. It is best to simply make sure that you have enough power for the CPU. If it uses say 130W or more, then it's best to use an 8 pin slot and an 8 pin connector. Any less for CPU power consumption and it doesn't really matter.

For example, where you mentioned the FX-8350 at 5GHz, you are right in that it is best to have an eight pin connector. However, no modern CPU needs an 8 pin connector and slot unless it is overclocked and many (especially Intel's Ivy Bridge CPUs) can still get safely away with a 5 pin even when highly overclocked.

The power supply needs to be matched for the job. For example, a system with an FX-6300 that doesn't have a huge overclock (maybe brought up to 4GHz or so) and a Radeon 7850 and otherwise low-power components such as a basic motherboard, storage, and such will be fine on an Antec VP-450W. However, as said above, some PSUs lie. For example, although Antec's VP-450, a 450W PSU, is enough, many 600W PSUs are not simply because wattage is not actually the important number, rather that would be +12V amperage, and many such PSUs lie about their power delivery anyway. Examples of such liars can include RAIDMAX, Logisys, and many more.

TDP is a term related to maximum heat generation and such, so it's only loosely related to power consumption. Maximum load power consumption is a little more difficult to quantify because even parts of the same model can have a little variance in their power consumption. TDP is also not necessarily even true. It's oftentimes greatly exaggerated for safety's sake and simplicity.

EDIT:
@unksol

I'll also say this to you: I make a very decent amount of money off of selling home-built computers. I have to sell a lot of them to make any serious profit, but it works, especially as a hobby that pays for itself. I wouldn't recommend that anyone try to make their whole living off of it, but there is money in it.


Thanks, man! I read everything else, and I knew that you always wanted to go larger on the power supply by a certain amount, as well as to NEVER skimp on the PSU, but your answer just nailed what I was specifically looking for! Thanks to everyone though for helping!
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a b V Motherboard
March 21, 2013 10:00:40 PM

Glad to help :) 
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a c 100 V Motherboard
March 21, 2013 10:51:31 PM

Pinhedd said:
Short answer: You only need 8 pins for very powerful processors. 4 pins is plenty for anything drawing under 150 watts.

Long answer: Be careful when you talk about 4 pin EPS connectors. There is a 4 pin EPS connector, but it is not synonymous with the 4 pin ATX connector. The 4 pin EPS connector is known as the 'tertiary' connector whereas the 8 pin EPS connector is known as the 'auxiliary' connector. The 4 pin ATX connector is known as the 'auxiliary' connector in the ATX specification. The 24 pin main connector is identical for both.

The tertiary 4 pin EPS connector is optional and will only be found on high end, high current power supplies. It's purpose is two fold. First, on high end motherboards and servers it works in tandem with the 8 pin EPS auxiliary connector for a total of 12 auxiliary pins. Second, on motherboards that are not EPS compliant, it can be substituted for the ATX12v 2.x 4 pin auxiliary connector. Since the 4 pin EPS tertiary connector is optional, not all EPS power supplies have it. Instead, many will split the 8 pin EPS auxiliary connector into two 4 pin connectors which allows it to be compatible with a motherboard that is only ATX compliant and thus features a single 4 pin auxiliary slot rather than an 8 pin auxiliary slot or an 8 pin auxiliary slot plus an optional 4 pin tertiary slot.

It is safe to overclock anything short of a SandyBridge-E with just a 4 pin connector, but I wouldn't try and win any competitions with it.



Very good response. But don't forget all the AMD CPUs. Thuban, Bulldozer onwards can burn out a 4 pin connector when overclocked (yours truly deals with customers so knows..hehe). I'd recommend everyone uses 8 pin EPS on boards that support the connection as a bare minimum, just to be on the safe side.
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July 14, 2013 11:09:14 PM

Are you guys sure running an 8-pin motherboard with a 4-pin connector is fine for a low-end CPU? I was having reboot problems under load with only the 4-pin connected. The problem went away after connecting the other 4-pin connector. The CPU is only an AMD A6-5400K. See this thread:

http://www.tomshardware.com/forum/id-1733746/pin-cpu-co...
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