lower power cpu == normal cpu when undervolted?

All about them.

Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee

Post Reply
bbzidane
Posts: 94
Joined: Wed Mar 26, 2003 3:25 am
Location: Kirkland, Washington

lower power cpu == normal cpu when undervolted?

Post by bbzidane » Thu Oct 01, 2009 7:14 am

I was wondering if low power cpus have the same power consumption as a normal cpu with the same architecture and clock speed when undervolted in general?

i just want to know if it is worthwhile to wait for the low power amd 240e or just get the normal amd 240 if im going to undervolt.


thanks

idale
Posts: 109
Joined: Wed Apr 22, 2009 7:06 am
Location: Austin, TX

Post by idale » Thu Oct 01, 2009 8:17 am

Generally it does seem like the lower-TDP versions of CPUs are "the same" as undervolted standard versions of the same CPU. What the lower-TDP version gets you is factory-guaranteed and defaulted undervolting, so you know that you can reach that level (as opposed to undervolting a standard-TDP CPU where some systems might not allow undervolting or the particular sample might not undervolt quite so low). I believe that usually undervolting on AMDs at least will disable Cool'n'Quiet, though that may or may not matter all that much depending on what you're doing and the levels you end up at.

So you definitely should be able to get a 240 and undervolt it to have what amounts to a 240e.

barefootzero
Posts: 102
Joined: Tue Apr 19, 2005 7:15 am
Location: san diego, Ca.
Contact:

Post by barefootzero » Thu Oct 01, 2009 8:19 am

I believe that is the case but there is a caveat.

Even if the 240e is a undervolted 240 AMD may have tested the chips to see which ones unervolt the best and made those 240e while the ones that did not undervolt as well were designated vanilla 240. So even if the 240e is just an undervolted 240 you would not necessarily be able to undervolt the vanilla 240 to the same level.

Its just like with clock speeds where AMD or Intel will test a batch of chips to see which ones came out the best and sell those at higher clock speeds then ones that did not come out as well. Nanofab is a fickle process so these sorts of variations in performance are totally normal.

That being said, I am very happy with my 240 and depending on the premium they charge for the 240e I may or may not have bought it had it been available.

barefootzero
Posts: 102
Joined: Tue Apr 19, 2005 7:15 am
Location: san diego, Ca.
Contact:

Post by barefootzero » Thu Oct 01, 2009 12:29 pm

idale wrote: I believe that usually undervolting on AMDs at least will disable Cool'n'Quiet, though that may or may not matter all that much depending on what you're doing and the levels you end up at.
My MSI 785gm-e65 w/ Athlon II 240 did not disable Cool'n'Quiet when i undervolted it. I can clearly see the multiplier and voltage change in CPUz when the workload changes. I don't know what any other boards are like and it may not work with other CPUs but this combination does work.

idale
Posts: 109
Joined: Wed Apr 22, 2009 7:06 am
Location: Austin, TX

Post by idale » Thu Oct 01, 2009 12:39 pm

barefootzero wrote:
idale wrote: I believe that usually undervolting on AMDs at least will disable Cool'n'Quiet, though that may or may not matter all that much depending on what you're doing and the levels you end up at.
My MSI 785gm-e65 w/ Athlon II 240 did not disable Cool'n'Quiet when i undervolted it. I can clearly see the multiplier and voltage change in CPUz when the workload changes. I don't know what any other boards are like and it may not work with other CPUs but this combination does work.
Good to know. It may be that it used to (whether due to chipset/BIOS limitations or CPU limitations), but should work on current hardware. I know the tower I've got (KN9 Ultra and X2 3800+) won't let CnQ work if you modify the CPU settings, but that's not exactly current on either end (not ancient as it's an early AM2 setup, but hardly qualifies as current).

RBBOT
Posts: 93
Joined: Thu May 17, 2007 9:02 am

Post by RBBOT » Thu Oct 01, 2009 12:57 pm

I believe the way it works is a range of chips share the same design. As batches roll of the production line, chips are tested to see how well those specific chips work at a range of clock speeds / voltages, then based on their performance results they are configured as extreme edition, low voltage models or standard models post-testing.

loimlo
Posts: 762
Joined: Thu May 03, 2007 3:58 am
Location: Formosa

Post by loimlo » Fri Oct 02, 2009 11:15 am

idale wrote:
barefootzero wrote:
idale wrote: I believe that usually undervolting on AMDs at least will disable Cool'n'Quiet, though that may or may not matter all that much depending on what you're doing and the levels you end up at.
My MSI 785gm-e65 w/ Athlon II 240 did not disable Cool'n'Quiet when i undervolted it. I can clearly see the multiplier and voltage change in CPUz when the workload changes. I don't know what any other boards are like and it may not work with other CPUs but this combination does work.
Good to know. It may be that it used to (whether due to chipset/BIOS limitations or CPU limitations), but should work on current hardware. I know the tower I've got (KN9 Ultra and X2 3800+) won't let CnQ work if you modify the CPU settings, but that's not exactly current on either end (not ancient as it's an early AM2 setup, but hardly qualifies as current).
Franklying speaking, CnQ or Speedstep is a feature that turns out to be board by board specific when overclocking/overvolting/underclocking/undervolting. That's the reason why extreme OCers must disable Speedstep/CnQ -- motherboard itself would disable energy-saving tactics when doing crazy things. :(

Fortunately, there's 3rd software solutions, ones like K10stat and CrystalCPUID, on AMD side. On the other hand, you're at the mercy of motherboard's Speedstep implementation on Intel side. Anyway, the bottom line for my lousy words is that exotic Speedstep/CnQ info are very scarce or next to none across the reviews or forum discussions .....

Catching
Posts: 24
Joined: Mon Oct 12, 2009 5:11 am
Location: California

Post by Catching » Mon Oct 19, 2009 11:55 pm

I am confuse about low power and normal power cpu? whats the differnce between on both? anybody can define me? is it voltage 120 and 240 difference or something else?

Ksanderash
Posts: 353
Joined: Sat Oct 18, 2008 6:30 am
Location: Moldova, exUSSR

Post by Ksanderash » Tue Oct 20, 2009 2:09 am

Catching wrote:I am confuse about low power and normal power cpu? whats the differnce between on both? anybody can define me?
Low power = selected. They simply choose the most stable working on low Vcore crystals. Then goes package, labeling, and selling at a higher price. You can undervolt the regular CPU by yourself, and it will be low power. But, most likely, it won't beat the selected one :)

CA_Steve
Moderator
Posts: 7470
Joined: Thu Oct 06, 2005 4:36 am
Location: St. Louis, MO

Post by CA_Steve » Tue Oct 20, 2009 6:40 am

RBBOT wrote:I believe the way it works is a range of chips share the same design. As batches roll of the production line, chips are tested to see how well those specific chips work at a range of clock speeds / voltages, then based on their performance results they are configured as extreme edition, low voltage models or standard models post-testing.
Yep. That's how it works.

Post Reply