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Topic Title: Undervolting: Solution or Mistake?
Topic Summary: Hidden Disadvantages of Undervolting?
Created On: 09/17/2008 04:27 PM
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 09/17/2008 04:27 PM
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Moomanerism2
Stanley Hudson

Posts: 274
Joined: 09/17/2008

Hey,

I'm unsure whether this has been posted, but the search yielded no results.

Upon seeing my HP Pavillion ZE2000 series laptop just about burst in flames, I decided to dig a little deeper into some sort of solution to lower the temperature of my ML-34 CPU. Every surface surrounding the keyboard was radiating heat, just like a giant heatsink, but that made no sense. The fan would constantly run at 100%, even with a USB cooler pad under it.

The BIOS, even on the most recent release, dictates that the ML-34 should boot at 1.45 Vcore. This made me scratch my head. Why would a 35W part need 1.45 V? Using a n00b tool (CrystalCPUID), I adjusted Vcore around 1.25V and went down from there. Temperatures dropped off the graph. Noticing a difference of about 15~17 degrees, I decided to push it a bit more.

1.200 Vcore was as low as I could go with the stock 9x multiplier. 1.175 was just too low to warrant 100% stability in all cirumstances, but with a lower multiplier such as 4x or 5x, 1.1 Vcore was stable. While this provides a great thermal platform for a laptop not used for gaming, I was still able to decode 720p video while having almost zero noise from the HSF because of such low temps.

OH! Unfortunately, it seems that the C n Q driver does nothing to lower the voltage, but more and more it looks like I'm somewhat of an isolated case.

What I'm interested in discussing are the potential downfalls of undervolting. In my research, it seems that stability is the only real issue, but could undervolting have some of the same adverse effects as overvolting/overclocking? Logic would say that there wouldn't be any, but I wanted to see what else everyone had to add.

Thanks!

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 09/18/2008 01:18 AM
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geezer_wheelz
Elite

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Hi
No under volting is nothing but good especially in your case
I tend to agree w ith you about it being strange that your CPU needs 1.45v!!
Under volted is just going to extend the life of your system
Make it as low as it will go and still be stable
Good luck

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 09/19/2008 09:17 PM
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billbartuska
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Originally posted by: Moomanerism2

...but with a lower multiplier such as 4x or 5x, 1.1 Vcore was stable.

..it seems that the C n Q driver does nothing to lower the voltage


What I'm interested in discussing are the potential downfalls of undervolting.


Setting the multiplier manually disables C&Q.
Change the FSB instead, if your BIOS allows it. But be aware that lowering the FSB also slows down the memory too. But, again, if your BIOS allows it, you can set a divider to speed it back up again. If not, there was a program called A64Info (that has been pulled off the internets now) that will allow you to control the memory.

You may want to look into RightMark's RMClock utility. It's much more sophisticated than C&Q and allows an even lower multiplier (4X).
RMClock (formerly known as AMD64CLK) is a simple GUI utility designed for realtime CPU frequency monitoring and realtime adjustment of the CPU multiplier (FID) and voltage level (VID) of the supported CPUs via processor's power management model specific registers (MSRs). In auto-management mode it continuously monitors the CPU usage level (reported by CPU itself) and adjusts the CPU frequency and/or voltage level as required

Potential downfalls? Only one. You're giving out a big secret here!

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 09/24/2008 05:39 AM
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Superhal
Overclocker

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cnq needs to have both the drivers from amd and be activated in bios. it seems that cnq is the absolute best way to undervolt (other than downcore.)
http://forums.amd.com/forum/me...d=99410&enterthread=y

however, it seems a lot of hp/dell/etc computers lock their bios.

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 09/24/2008 09:15 AM
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Moomanerism2
Stanley Hudson

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Joined: 09/17/2008

Originally posted by: billbartuska

Setting the multiplier manually disables C&Q.


Unfortunately, the problem with C&Q wasn't that it wouldn't function, it's that the default voltages were incorrectly reported by the BIOS. Stock voltage with the stock multiplier should be 1.35v, but it boots at 1.5v and loads XP at 1.45v.

Change the FSB instead, if your BIOS allows it.


Meh, it's an HP craptop. I begged and begged for at least a fixed BIOS, but they wouldn't give me that or the unlocked one I offered to PAY for. lol

cnq needs to have both the drivers from amd and be activated in bios. it seems that cnq is the absolute best way to undervolt (other than downcore.)


Hal, C&Q is superior because it has realtime monitoring of CPU load. Using predetermined voltages and multipliers for a given amount of load, the minimum amount of energy can be used, but even they have slack in them. Say my ML-34 CPU was only stable at 1.45Vcore at my 9x multiplier. I couldn't complain about the extra heat. But, my point is that cooling solutions for laptops don't have to be limited to the applications that are provided for us. I have a very average CPU in terms of stability to get to 1.2Vcore, but the lowest voltage/multiplier combination C&Q provides is 1.40v at 4X. WOW

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Supporting the Underdog
Gigabyte GA-MA790X-UD4P
720 Phenom II X3 (Unlocked to X4) w Zalman 9700LED 3.76Ghz (17.5X215)
Corsiar 520w PS
HIS 4850 (700/1133) w Fatal1ty FC-ZV9
4 GB XMS2 6400 + 4 GB G.Skill 6400 4-4-4-15
2 Seagate 500GB 7200.11 + 150GB Raptor
Westinghouse LCM-22w3
Fatal1ty 1010 mouse
 09/24/2008 02:33 PM
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Superhal
Overclocker

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hmm, that's weird. mine sets at 1.06, and the lowest i can go manually (without changing cpu settings) is 1.14.

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