Power consumtion of AMD's rev E core measured!

Mikael · Post by **Mikael** » Thu Mar 24, 2005 7:32 am

Okay, I don't really trust this site with power measurements, but it still looks extremely promising:

http://www.gamepc.com/labs/view_content ... 252&page=1

Looks as if the higher TDP of the Opteron 252 isn't to much to worry about after all.

Tibors · Post by **Tibors** » Thu Mar 24, 2005 8:09 am

Well I don't want to include th MHz diff in my calcs to keep it simple.

291-236=55W AC
PSU eff. 80% -> 44W DC
mobo Vreg eff. 90% -> 39.6W DC
Dual opteron -> 19.8W DC per CPU

Mikael · Post by **Mikael** » Thu Mar 24, 2005 8:15 am

Tibors wrote:Well I don't want to include th MHz diff in my calcs to keep it simple.

291-236=55W AC
PSU eff. 80% -> 44W DC
mobo Vreg eff. 90% -> 39.6W DC
Dual opteron -> 19.8W DC per CPU

Yeah, forgot about the two CPUs...

Still looks fairly good, though!

yeha · Post by **yeha** » Thu Mar 24, 2005 9:55 am

and once again, amd's tdp specifications are proven inaccurate and completely confusing. why-oh-why did they give the 252 a different tdp than the other e-stepping opterons which sit in the sub-252 bracket?

the only possibility i can think of is that the tdp figures they quoted are for the dual-core versions of each chip - so the 252's 92.6 watt figure actually indicates the tdp of the "252d" or dual-core 2.6ghz opteron to be released some day. that would mean the regular 252 would only be putting out 46 watts or so, and looking at those gamepc figures it might be even less than that. how frustrating.

hvengel · Post by **hvengel** » Thu Mar 24, 2005 10:10 am

It appears that starting with the 252 Opterons will have PowerNow (Cool'n'Quiet). But the power consumption numbers did not reflect this as they could not get it to work. They did not say why but I suspect the the motherboard BIOS lacked support since this is a new Opteron feature. So with PowerNow enabled idle power consumption would have been even lower.

Post by **MikeC** » Thu Mar 24, 2005 10:12 am

Tibors wrote:Well I don't want to include th MHz diff in my calcs to keep it simple.

291-236=55W AC
PSU eff. 80% -> 44W DC
mobo Vreg eff. 90% -> 39.6W DC
Dual opteron -> 19.8W DC per CPU

Your calculations took me a while to figure out, but the light finally went on.

Maybe not enuf coffe this morn...

The difference seems so big it is a bit mind boggling. The test system had 2GB of RAM & a 6800 Ultra, which means the baseline for peripherals was probably well over >100W AC.