Please HELP (4-pin mobo problem)

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F.E.A.R.

[H]ard|Gawd
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Sep 30, 2005
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Hi all,

I want to move from my single core AMD system to a core 2 duo. I am testing out a DFI board that has 2 -4 pin connectors. The problem is that my PSU (hiper 580) only has one available P4 cable. The P4 +P4 (4 pin) set-up is as follows:

p4p4kw0.jpg


My PSU provides the 4 pin to the left which I have circled red. Adapters also provide the left configuration. I am on a tight budget and even though I know I should switch the hiper out I rather use it to power my mobo, chip and peripherals and eventually get a dedicated vga power supply for the higher end cards. I currently have an X1900XT. I have two concerns:
1. Is there an adapter out there that would provide the 4 pin layout to the right?
2. If I do find an adapter is there a concern with screwing up the power requirement?

I am stumped and need assistance please. If you also have another idea please let me know. Thanks!!
 
You can likely find such adapters, but they are not recommended. The new 8 pin connection is an EPS +12v connector, which reared it's head on server motherboards years ago, and now has come to the desktop with the advent of power hungry system components, specifically those PCI-E cards that feed off of the PCI-E slot itself. PCI-E rev 1 spec says that the slot must be capable of providing 75w of power through the PCI-E connection itself. There are other reasons as well, but as the move to multi-core systems, the addition of more powerful bridge chips on the motherboard, more RAM slots, etc. Your current power supply should work on the new board, utilizing the 4pins that you currently have available. I would recommend, however, that you look at the product manual, online, to determine the implications of only using the P4 12v connection. Some boards will actually not post, others yet disable available RAM slots, or disable PCI-E slots, or SLI functionality (not likely to be an issue for yo, as you're using an x1900). I'd double check, just to be sure, but most boards will post. Some even have the option of using the 4pin P4 connector + a 4 pin MOLEX connector, in lieu of the EPS +12v
 
More pins is to reduce the contact resistance and double the current capacity thru this connector. If you use a 4-to-8 pin adapter you simply add some resistance to the 4pin instead of reduce it.

So the answer is, if your PSU only has a P4 connector, just use it and leave the other 4 pins of EPS12V unconnected.

The other 4 pins are usually connected to the +12V1 "rail" so there's a difference on a OCP-related calculation if you make use of them by using a PSU with an EPS12V 8pin connector. Since you might seldom meet with the OCP problem this is minor concern.
 
If that power supply would keep a power hungry P4 running (100-140 watts load and more OCed) it will easily power any C2D regardless of OC (80 -120W highly OCed), even a quad (stock or minor OC) with your current video card should not be a problem

I am confused with your diagram but thats just me. If you existing 12V aux connector will fit in one side or the other of the 8 pin MB connector on the board you are good to go, no adapter needed. Check you MB manual it should have a blurb about this as you are most certainly not the first person with this issue. But I am not sure I am understanding you, wish you had mentioned which DFI board so I could take a look see. (or a link to a picture). I hope that makes sense because one way I read your post is that the motherboard has 2 - 4 pin aux power connectors that are not side by side which is totally weird.


http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=85

Not too flattering. I would be sure to upgrade when you get a chance but for now you are just fine.

out I rather use it to power my mobo, chip and peripherals and eventually get a dedicated vga power supply for the higher end cards.
Click to expand...

Don't care much for that idea with the findings of the review above. You are fairly weak on the +12 for a high end system and the supply (yours is probably not a Type M which I assume is the modular cables but I bet the guts are exactly the same) has some issues. But thats your call. Power requirements are dropping or holding as the die shrinks give us more computational power with less electrical power draw but I just don't like what that review found for long term use. I would have a backup handy or think about modifying the cooling.
 
Thank you all for the responses. I am trying out a DFI 975X with an E6600 OC'd to 3.22.
I think I'm leaning towards a new PSU.

PS. The two 4-pin are right next to each other.
 
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