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

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tyler539

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Feb 22, 2013
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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!
 
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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...
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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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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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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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Solution


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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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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i can certainly back you up on that one, i recently had a phenom ii x4 955 with no overclock destroy a 4 pin to 8 pin adapter, there was no short but it just melted the cable, first thing we knew of it was a horrific smell and a room filled with smoke, everything still runs but cpu now has thermal runaway which even liquid cooling ha not solved, luckily it has not gone over 70c but idles around 57-65c and luckily i only use it as a bedroom media pc and light gaming
 
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Please don't necro post. This thread is over two years old.

Also, if a stock Phenom II X4 955 is melting 4 pin connectors, regardless of an adapter (which makes no sense unless it has more plugs feeding it, like a 4 pin and two 4 pin Molex or two SATA connectors), then there is something wrong with the CPU or the cabling was defective/poorly manufactured. It should not be pulling nearly enough power to melt a standard 144W rated CPU power connector.
 
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I notice experienced posters on quite a few sites now frown upon "necro" posting, but I think this idea is sometimes misdirected. What we don't want is unrelated, un-illuminating posts (of course). However, in searches, I've frequently come upon threads that will go down a road and end by being pretty useless--leaving off important information or insights that may have emerged later. In those cases, an update could be just the thing.

The March, 2013 post here marked as solution was in fact very helpful and answered most of what I wanted to know when I searched about 4-pin vs. 8 pin power connectors. Still, the July, 2015 post about burning out a 4-pin adapter made the issue much more vivid as to potential limitations of a PSU and plugs. The reply was helpful (ironically) despite the admonition about necro posting. I understood better what my expectations should be for power supplied to CPU power cables, what might make one fail or indicate a CPU problem. So,...thanks again--The thread became more useful to me than before.

Well,...apologies for not adding anything informative to the thread myself. :-/ I don't know where else a meta-comment like this would be more appropriate than where it comes up.
 
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Ok, I can see this post is old but let's just say I woke up late.
I have an ASUS M2N32 SLi Deluxe motherboard which only has a 4 pin auxiliary CPU feeder (the EPS connector, as you call it)
I've recently upgrade it to an "unofficial" Phenom X4 965 3.4GHz 125W TDP CPU, and I'm calling it that way because the latest CPU officially supported by the BIOS was the Phenom 955, with 95W TDP.

I've read the entire list of Phenom CPUs supported by my mobo and found out some of the first Phenoms (from the first generation) were also 125W TDP capable.

I have no desire to overclock what so ever, I already feel that those 3.4GHz really make a breakthrough (regarding the old Athlon X2 I was used to).
My only concern is to use this CPU at 1.35V and 3.4GHz with that only 4pin auxiliary connector SAFE. Until now I have about 20h of flawless working state.

Will it suffice? Will it be a matter of time until something gets burnt? Will I have something to risk here?

FYI, the PSU is a Corsair TX650.

Thank you.
 
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We would have preferred that you open a new thread, but alright.

Short answer: That is a risk (for the board, not the connector), but nothing is guaranteed.

The 4-pin power connector is plenty for a 125W chip. That connector is rated for 144W and that includes a safety factor since the 18 gauge wires and connector are physically capable of considerably more. The only concern I'd have with using a CPU that is over the recommended wattage of the board is with the power regulators on the board. The board wasn't necessarily made to handle the extra power and it can misbehave as a result. Sometimes that causes early failure of the board because it's delivering more power than it can safely handle for too long. Sometimes the board doesn't deliver the full power that the CPU wants instead and that can lower performance and/or cause system instability.

The Phenom II CPus that have 125W TDPs might actually use more power than the Phenom II CPUs with the same 125W TDP. Keep in mind that TDP and power consumption are not perfectly related and the way TDP is rated can be different between different generations.

Also keep in mind that for each model number, there are sometimes multiple models- a regular (locked) CPU and a Black Edition (multiplier unlocked). The board might be rated for the regular models (which are mostly 95W for Phenom and Phenom II), but not for the 125W Black Editions with the same model numbers.

Nitpicking: The 4 pin CPU power connector is not an EPS connector. The EPS connector is the 8 pin connector, which is rated for twice the power (288W). The 4 pin connector is sometimes called the P4 connector.
 
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Sorry for using the same thread. It's just that all my other forum subscriptions strongly encourage me to search for the problem and in case I find it anywhere, they compell me to continue my story there. My bad.

Ok, so the connector itself provides the necessary power, but maybe -just maybe- the power isn't necessarily sustained. This I can understand from your words.
Should I be worried in long term usage (as in prolonged uptime - which is not the case) or even in short usages, about 2-3 hours of intensive gaming could harm the board somehow ?

For starters, I'm not into the overclocking business. I've already spent a lot of anger resources just making the bloody thing work at full speed. It took me about a week, but using PMT it really uses that multiplier correctly.
Second of all, the board manual (ASUS M2N32 SLi Deluxe) states in multiple instances that (9 year old) innovations like "6 phase power design" and "cool vrm heatsink design" is really up to the challenge of heavy processing power. Now I realize they weren't reffering to Phenom IIs, but I believe they weren't that far of the thruth either.

What CAN I tell for now is that I've been extensively using testbenchs like Mersenne Prime 95, 3D Marks and AIDA's own stress test and it really provides a cool, unexpectedly stable operation. I can even monitor the voltage provided to the CPU (and several other components) and I must say it's a heavy solid straight 1.35V line; for hours and hours.
Looks like the electronics inside the TX series really stands out and earns it's money.

What I can also expect though, for the worse, is the breaking of the cheap looking capacitors... I mean my jaw dropped when I saw those things mounted on the mobo when I bought it ; for a flagship product that was so expensive, not using japanese quality really was a downside.

Anyways, today I've bought myself a GTX 770 and in addition to this Phenom CPU it really REALLY makes this old rig play the latest games with enormous ease. It's like my rig has been reborn, and after almost 10 years it can actually keep pace with nowadays trends.

I'm rather satisfied with how things are evolving regarding my configuration and, since the purchases are done, hope only for the best.

I managed to get hold on a Gigabyte Ultra Durable AM2+ mobo with an EPS connector just in case this one breaks down. :)

Thank you for your very comprehensive answer. I owe you one.

Best wishes.




 
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Made an account just to tank you for this answer.
Just got a motherboard that has an 8 pin ATX port and wasn't sure if I needed to buy a new PSU or not since mine only has a 4 pin power, but since I'm using an FX 6300 it sounds like it's enough.
 
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