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AMD and Intel CPUs that used +5v rail - help needed

M

mnemonik23

Member
Hello fellas and Happy New Year!

I have one question that I need your help with:

Which CPUs from AMD and Intel were powered by using +5v rail?


Thanks!
 
Practically any CPU that used a AT power connector (ie: any with an AT motherboard) were powered by the 5 volt rail on the standard PC power connector back then.

If you mean nowadays, practically all ATX CPUs still get 5v from their power connector, be it 20 pin or 24-pin, and some also need a 12v auxiliary power connector for extra juice for the CPU. If you could narrow your question down it'd be a little help but in the meantime I'd point you in the direction of this website:
http://www.playtool.com/pages/psuconnectors/connectors.html
 
No, almost all the CPUs from the last few years use 12V more or less exclusively. As far as I know, the last ones to run off 5V were the Socket A Athlon XPs and Semprons.
 
Right, modern CPUs use +12V.

I know it depends on motherboard, but which sockets were affected by +5V? I mean whaich sockets were capable of running either from +5V or +12V?

 
If a motherboard has the "ATX12V" connector (the 4-pin square one with 2 +12 V wires and 2 ground wires), it powers the processor from the 12 V rail. This is also called the "P4" connector because it was introduced with the Pentium 4.

All Socket 423 and 478 boards I've ever seen have had this connector. Ditto Socket T. Many Socket A boards do, but not all. AFAIK all Socket 754, 939, 479, M, S1, AM2, F, J, 603, and 604 boards (IOW, everything since Socket 423 for Intel, and everything after Socket A for AMD) use the 12 V rail. All near-future sockets (AM2+, AM3, etc.) should as well. Some boards have a Molex connector in addition to (or possibly instead of) the ATX12V connector, to provide compatibility with older supplies.

Older ATX boards (Socket 370, Slot A, etc.) should all use the 5 V rail.
 
Interesting thread.

I thought the ATX 12v was extra juice for the graphics card. I've built C2D, and X2 systems with the standard 20 pin ATX connector, and left the four extra pins empty with no consequences. Granted, they have very modest graphics cards.


Aluvus: I have built three socket 754 systems that only have the standard ATX 20 pin connector. 😉
 
Originally posted by: Amaroque
Interesting thread.

I thought the ATX 12v was extra juice for the graphics card. I've built C2D, and X2 systems with the standard 20 pin ATX connector, and left the four extra pins empty with no consequences. Granted, they have very modest graphics cards.


Aluvus: I have built three socket 754 systems that only have the standard ATX 20 pin connector. 😉
Click to expand...


Thats the 24 or 20 pin atx connector, the p4 connector is the separate 4 pin one which has nothing to do with the 24/20 pin connector.
 
So if you have a Socket A board with the P4 connector, what's going on? If the processor uses 5V, what's the purpose of the P4 12V connection?
 
Originally posted by: Towermax
So if you have a Socket A board with the P4 connector, what's going on? If the processor uses 5V, what's the purpose of the P4 12V connection?
Click to expand...

The processor is powered from the 12 V rail on those boards. But AMD did not mandate the extra connector on Socket A, so many boards kept on leaving it off (more connectors = more cost) and powering the processor from the 5 V rail.
 
Originally posted by: Aluvus

The processor is powered from the 12 V rail on those boards. But AMD did not mandate the extra connector on Socket A, so many boards kept on leaving it off (more connectors = more cost) and powering the processor from the 5 V rail.
Click to expand...

OK, thanks for the explanation--I thought it must be something like that.

 
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