ASRock Z75 Pro3 CPU throttle problems

[Grim Wrath]

Hello all, I am running the following system:
Intel i5 2500k @ 4.5Ghz
8GB of DDR3 Ripjaws RAM
EVGA GeForce GTX 680 Videocard
Corsair HX750 PSU
HT OMEGA Claro Halo Soundcard
HAF 932 Advanced Blue Edition case
Hyper 212+ Cpu cooler with push/pull configuration

Now, I'm trying to go for a stable, modest, 4.5Ghz overclock from stock 3.3Ghz. I have only changed the multiplier from 33 to 45, set turbo mode to +0.004V, set the offset voltage to +0.005V, disabled all C states except C1, and disabled spread spectrum. The problem is, when I do a stability test on Prime95 using max memory torture test, the speed is throttled down to 3.3Ghz for a few seconds, and then jumps back to 4.5Ghz. As the test goes on, the throttling increases more and more, to the point where it is throttled at 3.3 for a good 10-20seconds before jumping back to 4.5. Now my max temps with these test hover around 75 degrees C and the Vcore I get is 1.328.

Why is it throttling the speed? What can I do to stop it? I've tried disabling the thermal throttle setting in the bios, but to no avail. Also using the latest bios.

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Re: ASRock Z75 Pro3 CPU throttle problems

If you have C1 enabled, you'll still get changes in the CPU multiplier. Have you tried your test with it disabled?

You're not getting thermal throttling, if the CPU temps you mentioned are correct. With C1 enabled, and the UEFI/BIOS settings that are used by most mother board manufactures to enhance over clocking (setting the turbo and power timers to infinite) you'll get odd results like yours with C1 enabled. If your CPU is not overheating, then disabling C1 should fix your issue.

[Grim Wrath]

Re: ASRock Z75 Pro3 CPU throttle problems

If you have C1 enabled, you'll still get changes in the CPU multiplier. Have you tried your test with it disabled?

You're not getting thermal throttling, if the CPU temps you mentioned are correct. With C1 enabled, and the UEFI/BIOS settings that are used by most mother board manufactures to enhance over clocking (setting the turbo and power timers to infinite) you'll get odd results like yours with C1 enabled. If your CPU is not overheating, then disabling C1 should fix your issue.

Disabled c1. Still got the throttling. Disabled Auto Cstate package management, didn't help. Disabled speedstep as well, didn't help...Finally turned LLC from 50% to 100%, and I got a lower voltage than the other tests, strangely. 1.1272V...but hey, throttle is still happening for those few seconds at a time. Anything else I can do?
EDIT:
I've noticed that the wattage is around 100-115W when the CPU is running at 4.5Ghz. Maybe the fact that it's so high over the 95W TDP has something to do with it? Or is that just the 100% LLC..

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Re: ASRock Z75 Pro3 CPU throttle problems

The 95W TDP is not a power rating, it is a rating of the amount of heat the CPU cooler must be able to dissipate to prevent thermal throttling from occurring. TDP stands for Thermal Design Power.

So all of these disabled: SpeedStep, C1E, All C-State options, C3, C6, etc.

I would set Additional Turbo Voltage to Auto, and Offset voltage to Auto, your setting may be limiting it. I wonder if your boards 4 phase CPU power is not enough.

Are all the Long and Short Duration Power Limits set to Auto? Same for the Current Limits?

BTW, what are you using to monitor the CPU frequency, temp, etc? If your OC settings are correct, at idle your CPU should be running at 4.5GHz.

[Grim Wrath]

Re: ASRock Z75 Pro3 CPU throttle problems

Sorry about not knowing too much about TDP, I am a noob. Yes, the CPU runs @ 4.5 on idle. But, changing the offset and turbo voltages to auto seemed to solve the problem until the 20min mark..Then the throttle began again. I keep my max power values at max (500). One question though. Why is the voltage LOWER when I apply full LLC? Isn't LLC supposed to ADD voltage? I'm using Intel's burntest now, faster and more thorough than prime95 I think.


normal

throttled

Burn test says I was stable through 10 runs on "Very High" Stress level. Throttling indicates otherwise.


Should I just lower my multiplier until it stops throttling? :\

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Re: ASRock Z75 Pro3 CPU throttle problems

The point or goal of LLC is to maintain a certain voltage under load, to keep it from drooping, or going down due to a high load. So it does not really add more voltage, although it may look like it does. Its purpose is to maintain a voltage, not increase it.

A value of 500 for the max power values may not be the same as Auto, which is usually equal to no limit. A numeric value may not be the same as no limit, but we don't know exactly how that BIOS is working with different settings. I would try Auto instead of a specific value, since a value might be a limit.

[Grim Wrath]

Re: ASRock Z75 Pro3 CPU throttle problems

Alright, tried auto with the same powersaving settings disabled as well as auto with offset +0.005 and turbo +0.004, and I still got the throttles. Temps didn't really go past 75 either. I guess it must be some kind of motherboard glitch or something. I'll probably wait for the next FW to come out and try that.

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Re: ASRock Z75 Pro3 CPU throttle problems

One thing I just noticed that seems strange, but does fit the issue of throttling, is the differences in GFlops you get during each run. For example, here is a quick run I did:



Note that my Speed does not change much at all, granted just three runs, but yours dropped by almost 9 GFlops by the third run, and dropped by almost 12 GFlops at one point, over nine runs. It looks like you have some kind of throttling after the first run or two, although you said it didn't do that, I think. I don't get it.

When IBT checks stability, they mean how consistent the CPU is operating, and that does not mean its speed. That Results number is what is checked, it should be the same or very close on each run. If it is, that is stable. They aren't looking at the CPU speed as a test of stability.

[Grim Wrath]

Re: ASRock Z75 Pro3 CPU throttle problems

Speed decreases over time because the throttling becomes more and more prolonged as time progresses. 4.5 for a good 2 minutes then dip to 3.3 for 3 seconds...then it continues, with optimal speed being maintained for lesser and lesser periods while the throttle stays longer.

[Grim Wrath]

Re: ASRock Z75 Pro3 CPU throttle problems

So I did a little research and found out others had this throttling problem too. They contacted ASrock and got this custom firmware update that solved the throttle issues. I contacted them and gave them the link to this thread as well, hopefully they respond with a solution...

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Re: ASRock Z75 Pro3 CPU throttle problems

Ok, sounds good, that makes sense. As I recalll when Sandy Bridge CPUs first came out, Intel had set limits for how long the CPU would stay at the higher Turbo multiplier speed, for thermal and possibly power usage reasons. That applied to any multiplier over the stock speed. Mother board manufactures had access to those settings, which could be changed, and set to "infinite", which means the time limit of the higher multiplier could be turned off.

It seems that on this board, the time limit was not turned off, and the update you mentioned fixed that. The time limit on this board might have been intentional, to make the higher priced boards worth their price. Or maybe the CPU power regulators were not thought to be strong enough, or cooled enough, to maintain constant high CPU multipliers. Just guessing, and I imagine ASR will contact you pretty soon.

[Grim Wrath]

Re: ASRock Z75 Pro3 CPU throttle problems

Here's an update, they replied, stating that a MOSFET overheat might be the cause of the throttling. However, my motherboard sensors maxed around 73C. I'm wondering if that's the limit for the MOSFET or if its still a mobo firmware issue. I gave them a reply explaining my results and asking about the temp limit on the MOSFETs. Also asked for that special fw if they have it <.<. Here's the screenie a second or two right after the throttle occured.



Will update once I get another reply.

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Re: ASRock Z75 Pro3 CPU throttle problems

Are you sure that 73C temperature reading is the MOSFET voltage regulators (VR)? I don't know myself, just asking. I did mention earlier the four phase (four VRs) main CPU power regulation on your board as a possible issue. My Z77 Ex 4 board has eight phase CPU power regulation, and is still considered a budget oriented board. Boards with 12, 16, 20 and more VRs (one new one has 32) are there for a reason. The VRs on your board have a heatsink, can you get some extra cooling on it to lower the temp?

If you get that FW, you may being using it at your own risk...

I do have one other potential setting change, if you have it set up like this, that may help. When you set the CPU multiplier, do you use "Per Core", or "All Cores"? I've read that on some boards, when multipliers are set Per Core, or individually, they tend to throttle sooner on most of the cores, as in three out of four in your case. That is related to how Intel intended "stock" Turbo multipliers to work, ie, one core could maintain a higher multiplier while other would not. Just a thought.

More thoughts, do your PS have a four or eight pin CPU power cable/plug? If just the four pin, your board may be starved for current/power under higher loads, depending on how the eight pin motherboard connector is connected to the board circuitry.

[yuu]

Re: ASRock Z75 Pro3 CPU throttle problems

In recent review of Z75 pro3 became clear that 2500K can run at maximum 4400Mhz offset -0.025V without throttling.

I suggest you do the same. Z77 Xtreme4 also throttled. it has to do with VRM temperature threshold set too low in early bioses or in hardware.

Less VRM phases means lower efficiency and more heat and with heat efficiency drops even more. 4+1 VRM compared to 8+2.

The 4 pin connector is posing the risk of melting the connector with 150 watt cpu under the Linpack load.

So precautions are set in place by asrock... No bios update should or could fix what lacks in hardware.

1155 cpus are compatible but really this Z77/Z75 is meant for Ivy bridge a cpu < 100 watts overclocked.

example:

lets take the base minimum overclock to be 2500K 1.2V 4.0Ghz that results around 100 watts under linpack11 or prime95 v27

So 4.4Ghz how much? you reckon?

1.32 volts needed for 4.4Ghz means you have 10% increase in voltage and 10% increase in clock.

power dissipated by a circuit increases with the square of the voltage applied.

How much? 100*(1.1*1.1)*1.1 results 33% increase in power consumption ~ 135 watts.

and so on. 20% overclock with 20% increase of voltage gives 100*(1.2*1.2)*1.2 ~ 175 watts.

take it to 5Ghz and consumption doubles and motherboard burns.. hope the +1Ghz was worth it.

Asrock should send you a 8+2 VRM motherboard instead. not a bios fix since yours is only able of 135 watts and you seem to be willing a little more than that. the 4500Mhz mark.