4pin CPU power for QX9650 enough?

howdid

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Jul 11, 2008
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Just bought a new Asus P5E- Deluxe Motherboard with a QX9650
turns out the motherboard's CPU power plug is broken

the bottom 4 is alright
but the top left has 1 pin that is messed up

As a result
i cannot plug in the 8 pin CPU power chord in properly no matter how i try
I can only plug in 4 pin

Already called up ASUS for an RMA
but does it make a difference 8 pin vs 4 pin?

would i be able to run the QX9650 just on the 4 pin?
I really don't want to wait any longer for this computer to be built
 

Vertigon

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Apr 3, 2008
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I would NOT rely on the 4 pin especially with this cpu. I have a QX9650 and have heard about stability problems especially when overclocked. If it is simply a matter of returning the board, return it. 8 phase power was developed for overclocking and high power cpu's. Try reading your manual, page 1-5 or this link:

http://event.asus.com/2005/mb/ailife_ge/02_1.htm

If you own a QX9650, don't make silly compromises especially when you don't need to.
I have mine running at 4.2Ghz on the stock cooler and believe me things get very sensitive after 3.8Ghz, so don't use the 4 pin connector.
 
The 4 pin power connector will be enough.
8 phase power is not related to the number of power pin connectors.

The ASUS P5Q Deluxe has 16-Phase power and will run a top end CPU just fine with either a 4pin or 8 pin power connector.
 
Wish I had the test equip to provide exact values. I don't so I'll use approx values.

The adaption of the 8 pin connector was for the "OLD" power hog - the Pentium D extreme. Recommend use is for CPU's requiring 125/130 Watts.

Not really a need for 4 pairs of wire. a four wire configuration using 20 ga wire is good up to 22 Amps (264 Watt load). 90 Watts equate to 7.5 Watts and 130 watts is still only 10.8 Amps. Next is the IR drop: at 7.5 Amps the IR loss is 0.011 ivolts, and at 10.8 A is 0.0162 Volts. IR lose for 8 wire connection would be halve - No biggy.

The real advantage comes from the IR losses at the connector itself. The contact resistance at the connector is greater than the wire resistance. Assuming a contact resistans of 10 milliohms (Def of Assume - to make an A-- of you and me) This is a wag.
in a 4 pin setup @ 90 Watt IR loss = 0.075 V, @ 130 W = 0.11 V
vs 8 pin .038 V and .055 V. These voltage loses increase as system ages due to oxidation (reason gold plating is used).

Side note: By reducing the current per pin, it reduces the heating of the individual pin.

Bottom line, for CPU's drawing less than 130 W - 8 pin connector is not needed (unless your 12 V rail is on the low side inwhich case you should replace the PSU), But If you have the choise I would use it.
 
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WR2 good chart
Based on that graph 4 pin should be good up to 100% CPU load @ 3.8 Gigs

Not for wire ga I used 20 ga (standard chassie wiring) which 4 wire is good up to 242 Watts. I Think good PSU's use 18 ga, which is good up to 16 Amps per conductor (384 Watts for 4 pin. As Stated it is not so much the wire as it is the connector itself.