Weird i7 multiplier drops under load

[drivingon9]

Hi all,

I'm trying to test my my i7 950's OC limits (on a p6tdv2), and am hitting a weird issue with multiplier drops. I'd done hours of searching on the web, but haven't been able to find an answer, so I've come here in hopes of finding someone that can help me out.

I running at a 22x cpu multiplier with 190 bclk, which seems to be fairly stable for me. The issue that I'm seeing is that, while stress testing, the multiplier periodically drops down to 12x, then back up.

This appears to be indicative of a typical thermal throttle, but what's strange is that my max temps are right around 69-73 (as reported by real temp, hw monitor, asus bios tools, and core temps). Again, this is all under full load, during a prime95 run (i.e. doubtful to be a power saving option). It'll drop to 12x, then back up to 22x (after a minute, or two), stay there for a bit, then drop back down to 12x.

Anyone have any clues as to what could be going wrong, or what I could try?
Any hints would be greatly appreciated.

Thanks!

 

[Schmide]

Is Turbo mode disabled in bios? If it's on I think it limits the heat output to a 130w. I don't own a i7 but I've read about this.

 

[Ben90]

Originally posted by: Uncleweb

The P6T seems to start Turbo throttling somewhere around 4 GHz and 1.40 volts. The formula is based on current, power consumption as well as temperature so if you're air cooled and your temps are high then you might start to have this problem at a lower overclock.

Edit: Here's what the Intel Turbo White Paper says.

1.2 Dependencies / Algorithm
Intel® Turbo Boost technology core frequency upside availability is ultimately constrained by power delivery limits, but within those constraints, it is limited by the following factors:

? The estimated current consumption of the processor
? The estimated power consumption of the processor
? The temperature of the processor

 

[Idontcare]

I foresee this becoming more and more a topic in the forum in the months to come, maybe Gillbot or Mark should/could setup a sticky thread or mod the existing one dealing with EIST/C1E to include the topic of power-throttling (not to be confused with thermal throttling).

Originally posted by: drivingon9
I'm trying to test my my i7 950's OC limits (on a p6tdv2), and am hitting a weird issue with multiplier drops.

.snip.

This appears to be indicative of a typical thermal throttle, but what's strange is that my max temps are right around 69-73 (as reported by real temp, hw monitor, asus bios tools, and core temps). Again, this is all under full load, during a prime95 run (i.e. doubtful to be a power saving option). It'll drop to 12x, then back up to 22x (after a minute, or two), stay there for a bit, then drop back down to 12x.

OP, checkout this THG article on nehalem OC'ing and how the PCU actually throttles the chip by reducing its multipliers to below stock values while under load if the cores begin to consume the TDP for the chip (130W).

And so I scaled back to 3.8 GHz for our little throttling experiment. With Turbo off, the CPU TM Function turned on, and a 1.475V Vcore, I fired up Cinebench.

The benchmark got about halfway through and then stepped back to a 19.5x multiplier briefly. I restarted, set a 1.5V Vcore and repeated the procedure, this time catching multipliers as low as 18x.

So there?s Intel?s Overspeed Protection kicking in, just as Bert reported. Leave it on, and the processor will gradually step back its multiplier to keep you within its hard-wired ?safe? boundaries.

http://www.tomshardware.com/re...king-core-i7,2063.html

This type of power-throttling has nothing to do with thermal-throttling which means it has nothing to do with your cooling or the processor's temps. You'll run into this issue regardless whether you are on air cooling, water, vaporphase, or liquid He, etc.

There is a solution:

Now for the good news. Switch off the CPU TM Function in ASUS? BIOS (or the CPU VR Current Limit Override in Intel?s), and the capability stops interfering

You just got to figure out what the "feature" is called in your BIOS for your mobo maker and disable it (if they let you).

(credit goes to IntelUser2000 for making me aware of this active power-gating scenario on Nehalem-based architectures)

 

[Mr Fox]

Originally posted by: Idontcare
I foresee this becoming more and more a topic in the forum in the months to come, maybe Gillbot or Mark should/could setup a sticky thread or mod the existing one dealing with EIST/C1E to include the topic of power-throttling (not to be confused with thermal throttling).

Originally posted by: drivingon9
I'm trying to test my my i7 950's OC limits (on a p6tdv2), and am hitting a weird issue with multiplier drops.

.snip.

This appears to be indicative of a typical thermal throttle, but what's strange is that my max temps are right around 69-73 (as reported by real temp, hw monitor, asus bios tools, and core temps). Again, this is all under full load, during a prime95 run (i.e. doubtful to be a power saving option). It'll drop to 12x, then back up to 22x (after a minute, or two), stay there for a bit, then drop back down to 12x.

OP, checkout this THG article on nehalem OC'ing and how the PCU actually throttles the chip by reducing its multipliers to below stock values while under load if the cores begin to consume the TDP for the chip (130W).

And so I scaled back to 3.8 GHz for our little throttling experiment. With Turbo off, the CPU TM Function turned on, and a 1.475V Vcore, I fired up Cinebench.

The benchmark got about halfway through and then stepped back to a 19.5x multiplier briefly. I restarted, set a 1.5V Vcore and repeated the procedure, this time catching multipliers as low as 18x.

So there?s Intel?s Overspeed Protection kicking in, just as Bert reported. Leave it on, and the processor will gradually step back its multiplier to keep you within its hard-wired ?safe? boundaries.

http://www.tomshardware.com/re...king-core-i7,2063.html

This type of power-throttling has nothing to do with thermal-throttling which means it has nothing to do with your cooling or the processor's temps. You'll run into this issue regardless whether you are on air cooling, water, vaporphase, or liquid He, etc.

There is a solution:

Now for the good news. Switch off the CPU TM Function in ASUS? BIOS (or the CPU VR Current Limit Override in Intel?s), and the capability stops interfering

You just got to figure out what the "feature" is called in your BIOS for your mobo maker and disable it (if they let you).

(credit goes to IntelUser2000 for making me aware of this active power-gating scenario on Nehalem-based architectures)

Disable Turbo,..............It is a nice tool for the average Joe, but it is kinda a dumb item.


This Thread Will Help the O/P


http://forums.techpowerup.com/showthread.php?t=95282

 

[imported_Shaq]

Try disabling turbo and see if it still occurs. You can download a program called i7 Turbo that will allow you to monitor if turbo is turning off and allows turning turbo on and off from within windows instead of having to reboot.

 

[drivingon9]

Thanks for the responses, everyone.

I actually was using i7Turbo after seeing it in a thread that was related to my problems. I did play with the turbo settings in the software, but didn't have much luck. I finally found the option to turn it off in the bios (labeled just "TM"), and that seemed to do the trick. My multiplier finally stopped bouncing down to 12x.

Thanks, again, for the help. I appreciate it.

 

[Idontcare]

Yeah disabling turbo is not the same as disabling the over-current protection that moderates the CPU to prevent it from exceeding TDP.

The TM option did just that. It is called different things depending on the mobo maker and bios.

FWIW you can disable TM and enable Turbo and you'd be just fine too.