4 pin vs 8 pin 12V plug on PSU

[bgavin]

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

I found a place selling them for $3.35 each. Bought a couple, since the shipping was more than a single unit.

On a related note, I moved a Corsair 450VX out of a new workstation in progress, and into another new workstation for a different client. I really don't like this PSU in the Antec P182 case... cables too long, too messy. But, the 450VX is great inside an older Antec 830 (big) case. The P182 is getting a 520HX with modular cables.

The 450VX has the 8-pin as a split unit with two plugs. The harness is a single 8-wire type back into the PSU. The board it was feeding is a new GA-P35-DS3L that uses a single ATX12. I did a lot of research over at JonnyGuru on Corsairs... nice PSUs. KMR and KZE on the secondaries.

[travistee]

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

The reason I had this question is that I bought a gateway fx7026 that has a Q9300 quadcore. After the warranty is up, I'm planning to swap the proccesor out of this one with the D 820 that I will temporarily use in the Asus P5K-E.

The Asus has the 8 pin 12V.
The gateway uses The Intel® (Schroeder Town) G33 motherboard, has a 4 Pin 12V. http://support.gateway.com/s/MOTHERB...06194Rmv.shtml

I got a seasonic s12 550HT ($89) for the Asus, and I plan to replace the delta in the gateway with the antec tp3-430, since I think the deltas in a gateway probably are not the best deltas.

So... given the analysis of the 12 pin vs 8 pin why does the gateway have no problems with a factory setup using a 4 pin and the Q9300?

[PCBONEZ]

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

Q9300 is only 95 watts.
4-pin has two 12v wires.

95w ÷ 12v = 7.91 amp for CPU

7.91 amp ÷ 2 pins(wires) = 3.96 amps/pin

.

[bgavin]

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

I looked at the EPS12V 2.92 spec, and couldn't determine a current rating. 18ga wire.. anybody know the current limits for 4-pin and 8-pin?

[Wizard]

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

Current limit is actually in the contacts themselves plus run of wires and number of connections (soldered joints and other areas crimped but not soldered) adds up to certain resistance that limits the currents to a safe point. That is why it is specified in the intel design notes. Another reason to keep safe and max ripple to a minimum.

Plus 95W, 130W is high current at low voltage on this area and is best to have multiple connections or lower resistance plug (different!).

just over 9.5A for 12V for 95W and 130W is 10.8A. The connections/wirings from intel design and others said is about 5A or bit less per CONNECTION. And that's MINUMIM.

It is wise to overdesign to have stability.

My atom machines (two homebuilt machines using D945GCLF boards) have not enough filtering on 12V so I see noise and bounce at the 4 pin connection. Also filter more on -12 and -5 (yes I discovered that board uses this too!) I plan to add more capacitor to that area with inline wire capacitor when I get around to that. The symptom was keyboard and mouse locks up forcing power cycle or reset button if the hard drive is accessing and I was hitting on the launch icons during startup. If I wait longer till XP finishes with start up, no problems.

Cheers, Wizard

[PCBONEZ]

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

Current ratings for wire aren't that straight forward. (Unfortunately.)
Ratings are different for different temps, open to air or bundled or in a plenum (conduit).

The standards [UL, ANSI, MIL-STD, IEC, EN, and the others] that things like PSU's are built to comply with don't agree with each other. AWG 18 comes in anywhere between 2.3 and 16 amps depending on where you look.
-
Because the ATX Spec want's to comply with all of them they don't give a solid number.
- Just 'suggestions' and 'recommendations'.

You guys that like sleeved PSU wires are cutting you safe amps by 20-30% BTW.

Here is a blurb out of one of the ATX Design Guides.
-
ATX12V power supplies with the 2x2 +12V ......... are intended for applications where the motherboard demand for current exceeds the ATX main power connector capability of ~6 A per contact.
--------
"~6 A" - Is a quote ,,, "ABOUT" 6 Amps
- The ATX design guide won't even commit to a solid number.

They basically do the same thing with wire diameter:
"18 AWG is 'SUGGESTED' for all wires except the 3.3v sense return wire, pin 11 [22 AWG]".
--and--
"For 300 W [[and over]] 16 AWG is RECOMMENDED for all +12v, +5v, +3.3v, and Grounds."

"~ 6 A"
"Suggested"
"Recommended"

They don't lock in solid numbers because to do so might make them not in compliance with one of those Standards.

However,
You can guess from what they said that 6 amps per pin would be an ABSOLUTE maximum.

5 amps or less 'per pin' should probably be a working/target maximum.
Depends on how much safety margin you want.

.