Just a reminder that you'll probably have to be more careful about the PSU having a beefy 5V line than if you were building a regular socket 462 system... unless the processors' VRMs draw power from the 12V.

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Hopefully someone with more experience will chime in, but I'd probably hunt for something with 30A on the 5V rail. Assuming a 100% efficiency on the VRMs, two processors consuming 50W each would draw, by themselves, 20A from the 5V line. Then you have the rest of the motherboard and all attached devices and quickly even 30A doesn't look all that impressive.

From the manual:

Important Specifications: The minimum requirement for full-power loading is a 400 Watt ATX 12V power supply; minimum requirement […]
Show full quote

Important Specifications:
The minimum requirement for full-power loading is a 400 Watt ATX 12V power supply; minimum requirement for +5v/3.3.V is 180
Watts; +12 Volts requires 15 Amps; 5VSB requires 1 Amp. Also ensure that the ATX power supply can put out at least 10mA on the +5-volt standby lead (+5VSB). You may experience difficulty powering ON the system if the power supply cannot support the load. For Wake-On-LAN support, your ATX power supply must supply at least 720mA +5VSB.
NOTE:
It is recommended that both ATX power connectors be supplied to achieve adequate power.

http://dlcdnet.asus.com/pub/ASUS/mb/socka/760 … a7m266d-102.pdf

You have a 4 pin ATX12V connector and a weird 3.3 and 5V auxiliary connector. The unusual one will likely require an adapter.

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saturn wrote:

Is that 5v 3.3v thing needed if you use the 4pin cable? I'll have to take a closer look at the manual. I'm sure I can make one if need be. But what's the com pins for? Better not be some sort of sensor. Might be ground but I don't know.

I have a 650w antec psu I might be better off useing.

Generally they use AUX connectors to spread the current load out through more traces and power pins on the board.
I don't know if that board needs it but if it does and you don't use it you risk frying traces from or pins in the other power connector(s).

Do you know if that board powers the CPUs from 5v or 12v?
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What strikes me as odd is that the manual asks for 180W both on the 5V and the 12V rails. If the processor draws power from the 5V rails, why would it require so much from the 12V ones?

EDIT: Anyway, if the manual is so through as to indicate minimum loads on each rail, I'd not disregard that. Sometimes manufacturers overstate the PSU requirements, but in those cases they usually just say "400W PSU required" when a well balanced and nice quality 350W PSU would be more than enough, but it is because they need a large margin to compensate for poorly balanced and poor quality PSUs and users that do not have the necessary knowledge about the subject. A multi-processor system is aimed at a different segment (workstations, servers, etc.) and thus they can assume the system builder has adequate training.

alexanrs wrote:

What strikes me as odd is that the manual asks for 180W both on the 5V and the 12V rails. If the processor draws power from the 5V rails, why would it require so much from the 12V ones?

Indeed. - This board it a little odd.
I haven't quite figured out what's going on yet.

Looking at just +12v the manual says "+12 Volts requires 15 Amps".
A board of that vintage probably has the 9 amp pins so you need at least two.
Even with the newer 13 amp pins you'd still need two.
There is only one 12v pin in the 20-pin connector - so yes the 4-pin "P4" connector is required on this board.
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The 3.3 and 5 volt are going to be harder to figure out.
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It could be that ASUS calculated those numbers in a worst case scenario with the more power hungry Athlon XP processors - some had a TDP of almost 80W... imagine two of those together. Be sure to choose the processors carefully, as some Athlon XP-M had high TDP as well. This Wikipedia list should be a good starting point to getting a processor with a lower TDP.

AXP CPUs will not work unless bridge modded.

The MP's seem to cap at 66 watts TDP.

66w x 2 = 132w
Adjust for 75% VRM efficiency = 176w (from PSU)
(VRM efficiency was not that great back then.)

176w/12v = 14.7 amps (from PSU)

That fits the 15 amp @12v stated in the manual but it leaves no room for other 12v loads.
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/\ It also fits the 180W@5V (36A) specified above, but, again, leaves no room for other 5V loads. What a weird board. Still, since I assume most stuff on a motherboard (chipset, RAM, RAID controllers) draw from the 5V rails, I'd not doubt that the processor is being powered by the 12V rails.

I'm not sure about A7M266-D VRM configuration, but my Tyan Tiger MPX draws power from both 5V and 12V rail. Half of the VRM are connected to 5V (first socket) and the rest to 12V (second socket). Two Palominos 1600+ measured power consumption (CPUs only) is 95W combined on both 5V and 12V line (12,2A @ 4,56V + 3,2A @ 11,77V). That system was working flawlessly using 460W Delta PSU with 21A @ 5V and 15A @ 12V CPU / 11A @ 12V (second rail).

Or you could always get a motherboard with a bit more chest hair: http://www.tyan.com/archive/products/html/thunderk7xpro.html

You people are overthinking the power supply. A quality 500w one should be plenty and leave room for a vid card.

Barton 3200+ CPUs were drawing close to 30A on a 5V rail. Supplying the CPU rails with 12V VRMs is the only logical approach for dual CPU loads in this regime.

luckybob wrote:

Or you could always get a motherboard with a bit more chest hair: http://www.tyan.com/archive/products/html/thunderk7xpro.html

You people are overthinking the power supply. A quality 500w one should be plenty and leave room for a vid card.

That is all in response to the OPoster's question if the AUX connectors are actually needed.
To answer that we need to understand the board's power distribution.
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Me, I'd just use the AUX connectors - but that doesn't answer the question.
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