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[O/C]Load Line Calibration and You

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cool read

one of the better reads thanks to Bobnova
thanks to the oc benchmarking team for all their good posts.
Would be cool to have a scope on for a hour or so but that
might hurt your scope.
 
Nice article! I was never aware of that possible spike, but i'm glad that it's no present on higher end boards... i would assume that if those spikes really did happen at some point (Maybe before power regulation got so good?) the caps would smooth it back out before it hit the CPU.
 
i was wondering if you could do this test using IBT. ibt seems to have higher power requirements from my system so i'm wondering if LLC is being affected more from ibt than prime95.
i normally use ibt after running prime for 24/hrs. for some reason if i cut it close on voltages i can pass prime but not ibt.
 
A quick followup:
50us is the width of the screen, the minimum spike time to capture is something like 50ns if I recall correctly, very short indeed.

I've been meaning to repeat this with my P67a-UD4 and 2600K, maybe on dry ice if I'm really feeling hardcore.
 
try with a smaller timebase as well as mv/div, how can you actually see precisely at 200mv?

Its very hard to see that kind of voltage overshoot, and also why measure at the inductor's output? Why not measure at an MLC capacitor as output? i mean in real life the CPu is fed by the caps, not the inductors. Well yes the inductors feed the caps, but the amount of Vpp you are seeing is what 600mv? that is way to freaking much, your overshoot wouldn't even be 600mv!!!! acceptable ripple on these dc/dc SMPS is under 150mv.
 
Soo what would the general consensus (sp?) be on this?

I know I have been useing it since the p5b deluxe wifi was the shiznit, and I am still useing it to this day, and always on the max setting of course :D

Works good.
 
The general consensus I've seen recently (both here and at other places) is that it's not some super-destructive setting that will fry your CPU with voltage spikes. That being said, not everyone will need to use it, and TBH if you don't need it, there's no reason to use it. But if it helps your OC, go for it.
 
yea its not going to be harmful to your CPU in the shorterm, nor really in the long term. If you want your CPu to last as long as it can then it'd be wise not to use it, but otherwise its not going to cut the CPus life down noticeably shorter than your OC will.

In this day and age, SMPS design in terms of the PWM has come a long way since anadatech published that article.
 
Interesting article. I decided to play it safe and disable LLC, but it's requiring a 1.35 Vcore to run at my measly 3.6 GHz. My system wasn't stable at 3.8 GHz with 1.375 Vcore, so I know that the only way I'm going to possibly be able to push this system any further is by enabling LLC. Let's say that by enabling LLC, I am able to hit 4.2 GHz but I have to run at 1.4v. Is the benefit even worth the risk when I only use this PC for gaming?
 
How do your games run at stock clocks? That's the real question.

Personally I have run LLC of some level 24/7 and benching since this article and have yet to experience CPU damage because of it.
Or, for that matter, for any other reason. These have not been friendly skies my CPUs have been flying in either!
 
How do your games run at stock clocks? That's the real question.

Personally I have run LLC of some level 24/7 and benching since this article and have yet to experience CPU damage because of it.
Or, for that matter, for any other reason. These have not been friendly skies my CPUs have been flying in either!

Have you enabled it when your Vcore is at or above Intel's maximum spec (e.g. 1.4v for i5 750) on a 24/7 overclock setup?
 
So here is a strange thing that I can't find much info on and have no idea why it happens: When I enable LLC (setting enabled as opposed to auto) on my Asrock 970 Extreme3 (BIOS version 1.40) with a 955 Phenom II in it, the comp boots and initial CPU voltage appears normal (in fact, it is closer to what I set in BIOS than with it off). but, when I put a load on (such as a prime95 test), the voltage starts to DROP.

There seems to be some kind of rate limit on how fast it can change in either direction, but the voltage goes down... and down... and down. I'm not talking about just a little, I mean on the order of a 0.25V drop. Before I BSOD with LLC on, the lowest voltage I have seen it hit was 1.12V from a BIOS set voltage of 1.3375.

The exact opposite happens when I set LLC to disabled in BIOS. My initial voltages are higher (setting 1.3375 yields a BIOS HW monitor reading of 1.352V), and when I load the CPU with prime95, the voltages go UP. BIOS setting of 1.3375V yields a max voltage under max load of 1.375V as reported by both AIDA64, CPU-Z, and Asrock's tuner utility. All the software has exactly matched what the BIOS HW monitor shows for CPU voltage.

This behavior seems to be exactly the opposite of what I would expect. Has anyone else seen behavior like this?

PS: With LLC off and the load voltages going up, I am prime95 stable after 6 hours (longest I have run it, I don't like testing hardware while I sleep just in case). With LLC on and the voltages dropping under load, I error out on core 4 after 5 seconds to 2 minutes max.

EDIT: I meant to post this in a new thread on the AMD mobo forums, my bad.
 
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That sounds like a messed up bios, plus a defective board. Voltage shouldn't slowly do anything. When load hits it should go up or down immediately, and then stay there.
 
Voltage rate limit was a function of the monitoring software I was using. Tried some other software it is indeed instantaneous.
 
great writeup bobnova.
it shot down what i was thinking was causing my chv-f to freeze when closing programs when above 5.2 or 1.72 vcore.
also you made a fibber out of asus, the manual says that llc lowers the vcore under load to help control temps.
 
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