P-7805u, P8400, and CPU Undervolting

I have been adjusting my voltage with RightMark CPU Clock Utility and then stress testing the CPU with Orthos. The voltage that has proven most stable at this point is .9750V at 8x multiplier. My max temps are around 50 degrees Celsius as a opposed to 58 degrees Celsius, both under load.

How is this in comparison to you guys' P8400s?

 

Are you using the scaled (forget what it's called) voltages? The ones that go down and up with the multiplier? My 7811s voltages did that (don't have it any more so I can't tell you what they were) and my temps were 46-47c under full gaming load, and 26-27c just running desktop apps.

 

Yes, I am using P-State Transitions if that is what you are referring to.

 

I would raise the multiplier a little higher.

I play last remnant and it maxes CPU for hours and GPU. I heavily monitor and test. Under high cpu load you will get some choppy spots. To be safe I have it as followed right now. Again I have much more testing to do but so far so good 10+ hours maxed out CPU 100% and frequency 100% along with GPU maxed. I use orthos but you can't get real live conditions so I play last remnant as well if anyone has the game you will see it maxes this laptop out. I have done orthos for 4 hours no issues but 10 hours of last remnant and even right away you notice some things that is reason for raising it above what you have now. I had yours and it caused some things so did one up and nothing so far. Will report back if anything changes.

superLFM 6.0x 0.9250
normal 6.0x 0.9625
normal 7.0x 0.9750
normal 8.0x 0.9875

This is same P-state transitions set all at default.

Not sure idle as I have skype and hwmonitor and tons of programs that start on startup so not a good idle example so I have normal activity searching websites watching a video on yourtube etc.

Normal Activity:
CPUs 32 degrees Celsius
Chipset 45 degrees Celsius
GPU 45 degrees Celsius
HDD 40 degrees Celsius
These are peaks not average

On load (orthos 10 min):
CPUs 50 degrees Celsius
Chipset 64 degrees Celsius
GPU 50 degrees Celsius
HDD 41 degrees Celsius
These are peaks not average

On load (last remnant 10+min):
CPUs 49 degrees Celsius
Chipset 60 degrees Celsius
GPU 68 degrees Celsius
HDD 44 degrees Celsius
These are peaks not average

I do have a coolmaster cooler as well but didn't notice a huge difference when getting it only like 3-5 degrees Celsius from standard temps which my peaks where CPU 61 and GPU 81 degrees Celsius. Hope this helps someone. It did help HDD HUGE thought the coolmaster rest not so much as the airflow areas do not match up with any of the GPU or CPU. I am going to modify it to extend out to hit those locations though this week.

Also I am thinking of raising the values a little more but maybe only advanced multiplier 8x just because of stress with last remnent again you may not need to do this unless you play very stressful games. You can leave it on what you have but the temp gains are minimal so better safe.

 

How do you get RMC to go below 1.0125 on the P8400?
Custom P-States maybe?

 

You have to make sure you set MOBILE in advanced settings and the check mark below that. Then restart computer. It then will let you go laptop volts as before it defaults to desktop which wont allow you to go below what you stated.

Here is the guide I used:
http://forum.notebookreview.com/showthread.php?p=2637648#post2637648

 

Yep, that was it ... mobile. Thanks.
+rep

 

Just to let you guys know the above numbers for undervolting does hurt performance a little with the windows score test. Went down 0.1 but I don't mind at all cause of the safety temps I am getting. Didn't do any other tests on it cause I am worried more about longevity and temps being low then small hit to performance. I have since changed my values though to this so all depends on how much you push the machine to be honest.

superLFM 6.0x 0.9250
normal 6.0x 0.9750
normal 7.0x 0.9875
normal 8.0x 1.0000

Just understand volt ranges for CPU are 1.00V-1.250V so I am using lowest range now just to be safe and difference in temps are so minimal 2 degrees Celsius so mise well have it within spec.
http://processorfinder.intel.com/details.aspx?sSpec=SLB3R#

Again some people can go way lower with volts without issues all depends what you use laptop for and how hard you push it and for how long etc.

 

I am running at .9750V and the max temp I hit was 45 degrees Celsius. I have been able to run Orthos with the Max CPU Stress setting for 6 hours before I stopped it to do some gaming.

 

Yes, it does affect performance due to constant switching of clocks from the high no. of P states.

 

I disabled all other P states so that only the 8x multiplier with a .9750V runs at all times.

 

Performance hit on the P8400 is due to RMC not allowing full clock on CPU. There is no .5 multiplier.

 

The way the 7805 comes set from factory all the p states are the same. so i undervolted it and set them all the same.

 

I guess that works too

 

Try enabling IDA, half multiplier works with my T9300.

 

Can someone confirm this? And does it still hurt your performance. The P8400 is already a rather average cpu. I want to get everything out of it. How nice of Asus to let the 8400 be OCed to 2.5ghz

 

P8400 doesnt have IDA

You aren't going to notice the half multiplier being gone, the lower temps will make just about the same difference, regardless you won't see any difference at all and shouldnt be worried about it.

Setting all the voltages the same is basically an incomplete undervolt. The P8400 doesn't have many clock speeds (4 IIRC), it doesn't take much time at all to find the lowest voltage for each. Once you reach the lowest voltage allowed for a multiplier, THEN you can apply the lowest voltage allowed for each smaller multiplier, since it will always need less voltage.

That's what you want to do for the Maximal Performance profile

 

Great results, I'm using 0.9875V max temp 49º

 

That is the profile I use all the time. I like the full 2.26 Ghz available at all times - it makes the machine snappier.

 

There's no doubt that it works, I'm just surprised that you would want it running at full speed at all times. It will be slightly hotter and will use more power (That won't work well on battery).

My T9900 runs at 800MHz at all times except I switch it to 3066MHz when I play games. As soon as I'm done gaming, I switch it back to 800MHz.

A SSD would definitely help with the "snappiness" of it, but 2 7200RPMs in Raid0 isn't slow either

 

I still get over 2 hours of battery life using the Maximal Performance profile at all times. I consider that phenomenal for a laptop of this size and speed.

 

2 hours is alright but that is definitely shorter than you would get with a different profile. I am able to game at 800MHz with only a very small hit in performance, and even on the Performance on Demand profile while gaming I am able to play for over 3 hours. My setup is quite different than yours so it's comparing apples to oranges, although you could still achieve longer battery life with your setup with a different RMclock profile.

Whatever floats your boat, different strokes for different folks

 

Oh no, I agree with you fully. It has surpassed my expectations so far, even under the max profile. When I am on the go, I would use a different profile. I just unplug to give the battery some use every now and then when I am at home.

 

How come there have have no VID's i'm not even sure if the programs detects my cpu. Cause according to this guide, i was supposed to make it mobile. But afterwards the image is what i have. Is that normal?


quick question....this is an example so because on my profile(Image up top it doesn't show the voltage!?!?!), since me 6x, 7x, and 8x has the same VID if i lower 8x it would be lower then the rest. Do i do it to all three one at a time?

 

Pretty sure you just didn't click the Defaults button. The guide states to do that if your stock voltages don't show up.

Yes you can do all 3 at a time. The lower multipler will always use LESS voltage than the next highest multiplier.

Obviously once you've found the voltage limit for the 8x and start lowering the 7x, ONLY lower the 7x and 6x, you don't want to lower the voltage of the higher multiplier once you've already found where it's unstable.

 

I think someone mentioned that undervolting too much makes you lose performance? I just want to know performance lost as in what type. If thats true, should i disable the 6x and 7x if my 8x is at a stable low voltage? I see people running it at 0.97 or lower

 

Undervolting will not make you lose any performance. On certain processors you will lose the .5 multiplier, you will essentially be losing speed although it is not nearly enough to physically notice, and undervolting will more than make up the difference lost.

Every processor will be different, don't view other people's results and then expect your processor to be the same. Your temps will be different, and your stable voltages will probably be different as well. Use the guide for reference, you must find the lowest stable voltages of YOUR processor, don't copy the voltages others are using, even if they're using the same processor in the same laptop.

For the Performance on Demand profile, you want to use EVERY multiplier you have available.
For the Power Saving profile, you want to use just the SLFM.
For the Maximal Performance profile, you want to use just the highest multiplier.

Obviously you can set things up different/the way you wish, however this is the way the program was designed to be used, so this is the way I use it and I recommend it because it has been working great for me and has been 100% reliable.

 

But like, before i started to undervolt, all my multiples were using the same voltage. Would this change as i continue the undervolt or should i just leave them the same?

 

I attached below a few tests to show you results all same conditions ALL random testing order to rule out heating things up to be a factor. I let everything cool down for about 10 minutes or until it reached the base #s from before the tests which I am limited on attachments to post that image but you get the point.

What you will see from this is after you reach x8 multiplier 1.000 anything below it you will get very minimal difference in temperatures and MUCH higher risk of having issues with CPU. As I stated before some levels WILL cause glitches at certain levels. So to drop it below this value to gain 1-2 degrees Celsius makes no sense. Now the x6 multiplier dropping it down makes huge difference at system idle and no effect that I have experienced. Again the tests images will better explain the conditions etc. ALSO let me be clear this was in a hot room think around 85+ degrees (Fahrenheit) as I wanted to test it in extreme conditions to really see the difference.

Also to note I have bios .17 and all updated drivers and chip sets. I also have a laptop cooler which I just modified today to actually hit the CPU and GPU fan areas which I will post a new tutorial thread on that later.

My final Numbers are this:
0.9250 SuperLFM x6
0.9250 x6
0.9625 x7
1.0000 x8

I have not played to much with x7 as my CPU rarely ever hits it and depends on latency etc of switches you choose within the software etc. So I just put a random middle number.

 

Thanks man.

 

Just FYI this is on the performance on demand and I just have it load on startup. I hope the above info I have given helps people get an idea of what to do and so on.

 

Yes they will change, unless you hit the low limit of the voltage.

For example on my T9900 my 9x multiplier is very close to the lowest at 0.9125V, 8x is at 0.9000V (Lowest it can go), and so obviously the 7x is also 0.9000V, as well as both my 6x multipliers at 0.9000V, since they cannot go any lower.