CPU 3.3V-rail or 12V-rail?

[steimm]

I have a simple question, is it the 3.3V-rail that provides the CPU with power or is it the 12V-rail?

I'm reading from Tom's hardware something that I don't really understand, it say something about that it is the 12V that gives the CPU the power? Or is it just för the test that they have done that?

I have been told earlier that it is the 3.3V-rail that gives the CPU the power...

thx

/steimm

 

[Fun Guy]

I thought is was the +5v rail.

 

[pm]

Off the top of my head, I believe: it used to be the 3.3V rail on the Pentium. Then it became the 5V rail on the Pentium II and III. Now it is the 12V on the Pentium 4. As I recall these are for Vcore. Vio uses the 3.3V rail on all three.

 

[steimm]

Interesting, anyone that have more ideas?

And for the AMD-systems, is it any difference compared with Intel-systems? Ok, the P4-CPU should get power from the 12V shouldn't it?

I've found a couple of links that "talks" about the 3.3V-rail (and a little about the 5V-rail).

Overclockers NZ

Unofficial HardwareZone.com

/steimm

 

[CTho9305]

Originally posted by: steimm
Interesting, anyone that have more ideas?

And for the AMD-systems, is it any difference compared with Intel-systems? Ok, the P4-CPU should get power from the 12V shouldn't it?

I've found a couple of links that "talks" about the 3.3V-rail (and a little about the 5V-rail).

Overclockers NZ

Unofficial HardwareZone.com

/steimm

IIRC, the tyan dual socketA mobo required a LOT of power on +5... so i'd tend to think that AMDs run off the 5V rail. I am almost 100% sure that SLOT athlons don't run on 12V, because I messed around with the voltage regulator on a slotA mobo

 

[steimm]

One thing is for sure(?), there are not one and same rail that provides all the different CPU's with power. At least after reading the replies...

Is it anyone that can tell me what rail AMD T-bird, AMD Palomino, AMD T-bred, Intel Tualatins, P4 Willamette, P4 Northwood Celeron P4 etc. get their power from?

I've been trying to find the information on the net but without success...

Another link that say it is the 3.3V-rail that gives the CPU the power:
HWsource

But after making some calcs with the Watts that i.e. a AMD Palomino using, the +3.3V might not be be able to give the CPU enough power - at least with an 300W PSU that only has i.e. 20A on 3.3V?

/steimm

 

[steimm]

^