Drop in vcore voltage and clock speed

lessthanz3ro

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Oct 15, 2010
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So I've been noticing that my computer has been acting a little slower than usual, and my graphics card (radeon hd 4870) has seemed to not be performing as well as it has in the past. I do a little bit of investigating and find that my power supply is only outputting 10.18v on the 12v rail. Also, under load, my cpu clock drops from 3411 to 802 on each core of my phenom II x4 940 which is installed on an ASUS M3A79-T Deluxe. The drop in clock speed seems to be directly linked with the drop in vcore voltage from 1.47 to 1.01-1.02v. I assumed I had a faulty power supply so I replaced it yesterday with a brand new thermaltake 850w (which replaced my PC Power&Cooling 750) but I am now having the same issue. I used OCCT to get my readings, and I know software based monitoring of these values is not the best way to do it, but it definitely seems that I have a problem regardless. Even my benchmarks are almost half of what they should be as compared to similar systems, on the gpu and cpu sides. By buying the new PSU I ruled that out as being the culprit, but now I'm at a loss of what to do. Any insight on this problem would be extremely helpful. Thanks!
 

damasvara

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Jul 20, 2010
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Well, although this may not be applicable for you, you can try to use K10Stat to manage your CPU speed stepping and voltage at each steps. The reason I said it may not be suitable for you is because I personally use it for undervolting my CPU. In your case, you can set the CPU and NB Voltage to preset values, and fine tune it until you have the intended result. This is a software based solution though. May not work if you do have a hardware issue.

From your description, I assume you have the Cool n Quiet mode on in BIOS. The K10Stat itself acts like it, but fully customizable. If you find it necessary, turn off the C n Q and start working on the K10Stat settings.

Hope this helps. Good luck!
 

lessthanz3ro

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Oct 15, 2010
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Thanks for that info on the k10stat, it helped me somewhat narrow down my problem, although I'm not very familiar with how to use it. I checked bios and I'm getting a full 12v on the 12v rail, not 10 as stated before from using OCCT, but even in bios my vcore voltage is still dropping. I have CnQ and smart fan settings disabled in bios though and I am still having the problem. And in bios, when the vcore voltage drops, the 5v rail goes up a little. I don't know how else to stop it form doing a CnQ type thing where it changes the p-state. I set in k10stat so that on every p-state it would stay at the full clock speed and voltage, but I am still having the problem. Am I just not doing things right, or do I have a more serious problem? I had to go down a bit on the overclock too because my CPU was getting to almost 100c, which can't be good for it.
 

damasvara

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Jul 20, 2010
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I need to know:

1. What program do you use to monitor the vcore? HWMonitor from CPUID is the most commonly used.

2. What settings do you use for the K10Stat? Please post the p-states and NB voltages. Pictures if possible.

Since you're OC'ing. It wouldn't hurt of you set the settings to default and see if the issue still persists. The last resort would be to flash the BIOS, but only consider this if the other methods fail to resolve the issue.
 

loneninja

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I don't feel like searching for it on AMD's website, but I know the max temp for a Phenom II is between 62C and 71C, it varies between stepping. If your cpu is dropping speed/voltage under full load it sounds like your overheating and the cpu is throttling to prevent it's own destruction.
 

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