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Windows 7: Intel T7250 2.0 GHz multiplier stuck at 2.0x, Core Speed at 398 MHz

14 Mar 2012   #1

Windows 7 Ultimate x64
Intel T7250 2.0 GHz multiplier stuck at 2.0x, Core Speed at 398 MHz


First of all I'll tell you what I'm running:
Dell Inspiron 1520 laptop
Windows 7 Ultimate x64
Intel T7250 2.0 GHz
250GB Samsung Internal HDD

My old hard drive died recently, so this morning I switched it for a brand new replacement.

Upon reinstalling Windows it was clear that the computer was running dreadfully slowly, so I downloaded CPU-Z to see what the CPU was doing. CPU-Z says that the processor is running with an apparently unchanging multiplier of 2.0 (normally between 6 and 10 depending on what SpeedStep is doing) with a bus speed of 199.45 MHz, reporting a core speed of 398 MHz. Additionally, it's reporting a Core VID of 0.85V (the Intel website says that the range for this processor is 1.075V-1.175V)

When I boot into the BIOS it reports the CPU to be running at 2 GHz, and using ThrottleStop allows me to bring it back into normal range once Windows is loaded. The computer doesn't seem to boot any slower than before, but once it gets to the logon screen it slows down, which leads me to believe that it's somewhere there that is going wrong, perhaps? I've set ThrottleStop to load at startup, but isn't a foolproof solution and, really, I'd much rather have Windows manage the CPU than have to do it manually.

A second reinstall of Windows has not solved the problem.

If anybody has come across something like this before, or has any ideas for how to begin trying to sort it out then I will be very, very grateful.


My System SpecsSystem Spec
14 Mar 2012   #2

Windows 7 Ultimate x64

Hi again,

I've tried a couple more things.

Updating the BIOS (to the same version, so reflashing, I guess) increases the multiplier, according to CPU-Z, to 4x, but it doesn't go any higher than that.

I've tried uninstalling and re-installing the CPU drivers through Device Manager. When the computer restarts it runs to the full 10x multiplier (occasionally running up to 11x, which seems to be a kind of overrun that it's always done). This lasts for a minute or two then it drops back to 4x and refuses to go higher again.

All the while CPU-Z is reporting a VID of 0.85v despite the Intel website, and everything I can find online, saying that the minimum voltage for the CPU is 1.075v.

Using ThrottleStop is having the side-effect of overheating the laptop (because it seems to run at the high multiplier for a lot longer than it usually would) causing it to shutdown automatically at a certain point.

When I boot up the BIOS is still reporting the CPU to be running at the full 2GHz, which is the normal 10x multiplier, and it drops when Windows takes over.

Completely running out of ideas. I've never had a problem like this before with any version of Windows, and the computer was working absolutely fine yesterday.

I guess my next step is trying it with a copy of XP or something, to see if I can try and rule out the OS as a problem, unless anybody has any ideas at all for what to try before doing that?

Thanks again, any help at all is very much appreciated!
My System SpecsSystem Spec
14 Mar 2012   #3

Windows 7 Home Premium 64 bit

Have you tried going into the BIOS and loading the defaults?
My System SpecsSystem Spec

14 Mar 2012   #4

Windows 7 Ultimate x64

Hi there, thanks for your reply.

I'd forgotten to reset to default after updating the BIOS, but I've just done it now to check and there is no difference.

I've since ran the Intel Processor Diagnostic Tool, and it reports that it's finding a CPU speed of 2.19 GHz. The computer still feels slower than normal, so I checked again and CPU-Z continues to report that the CPU's multiplier is 4 and it's Core Speed is 797 MHz. Crystal CPUID reports the CPU running with a constant multiplier of 8, so I'm not really sure what's going on here. Something's odd.

Thanks again for your reply. If you or anybody else has any other suggestions I'm more than willing to try them.
My System SpecsSystem Spec
14 Mar 2012   #5

Windows 7 Ultimate x64

I should note that when running ThrottleStop I get a different result: the Intel tool, CPU-Z, and Crystal CPUID all generally report the same CPU frequency, although the CPU-Z reports when the CPU has been throttled back by SpeedStep and the Crystal tool doesn't report the same figure (CPU-Z will notice when it drops to 6x and reports it as 6x, Crystal doesn't report any change until CPU-Z thinks it's dropped to 2x with SpeedStep and then Crystal reports it as having dropped to 8x). In fact, ThrottleStop reports an entirely different CPU speed from both Crystal CPUID when the CPU is being throttled back.

This should give you an idea of what I mean:

Not sure how relevant this is, but I guess I should give you guys as much information as possible.
My System SpecsSystem Spec
14 Mar 2012   #6


Your CPU uses a feature called SLFM which stands for Super Low Frequency Mode. When your CPU enters SLFM, the front side bus (FSB) speed drops in half and the multiplier increases to 8. The normal bus speed for your CPU is approximtately 200 MHz. Most Dell laptops are around 199.4 MHz to 199.5 MHz as far as I recall but to keep things simple, lets say it is 200 MHz.

When your CPU first idles down, it will go to

6.0 x 200 MHz = 1200 MHz

when SLFM mode kicks in, the multi goes up and the bus speed gets cut in half. The result is this:

8.0 x 100 MHz = 800 MHz

This happens so quickly that it is difficult for software to report this correctly so CPU-Z cheats and reports this as:

4.0 x 200 MHz = 800 MHz

Same total MHz but CPU-Z doesn't accurately show you what your CPU is really doing. The lowest multiplier physically possible in the Core 2 design is 6.0. Any software that reports less than this is bending the truth a little.

Anyway, sounds like your CPU is running as designed. If you don't like SLFM mode then use ThrottleStop and turn it off. If you want to lower your CPU further you can combine SLFM and the minimum 6.0 multiplier for an effective multiplier of 3.0.

6.0 x 100 MHz = 600 MHz in SLFM mode which CPU-Z will report as 3.0 x 200 MHz = 600 MHz. Same total.

In Windows 7 you need to go into the Power Options and use the High Performance profile and set the Minimum processor state to 100% if you would like your CPU to not drop down like this when idle. You would also need to disable C1E.

ThrottleStop will not make your CPU over heat if you actually take some time to learn how to use it. ThrottleStop can be used to control the maximum temperature and speed of your CPU and can put you in full control.

When your multiplier goes beyond the default multiplier of 10, that is called Intel Dynamic Acceleration (IDA) mode. The way this Intel feature works is when one core goes to sleep, the other unused core will step up to a higher multiplier. The default multiplier for your T7250 is 10 so the IDA multiplier is set to 1 unit higher which is 11. When running a single threaded benchmark like Super PI, the multiplier will rapidly switch between 10 and 11. Whenever the second core wakes up to process some Windows background task and both cores are active, the multiplier drops down to 10. As soon as that task is finished and a core goes back to sleep, the multiplier immediately goes back up to 11. This happens so rapidly, hundreds of times a second, that most monitoring software can not keep up. ThrottleStop uses high performance timers within the CPU and can calculate an extremely accurate average multiplier when this is happening. You might be able to average close to the 11 multiplier when running a single threaded benchmark but you will never be able to run the full 11 multiplier for any length of time because there are always hundreds of background threads that need to be processed which immediately reduces the average multiplier because they need to wake up the second core.

Interesting technology. Intel took this idea and refined it and turned IDA mode into what is now known as Turbo Boost in their new Core i processors.

Almost forgot. 0.85 volts is typical when SLFM is being used. I think the typical minimum for these CPUs is 1.00 volts if you turn SLFM off. ThrottleStop uses the Intel recommended monitoring method when reporting the multiplier so you can trust what it is telling you. Run a single threaded benchmark like Super Pi Mod and use the task manager to lock superpi.exe to a single core of your CPU. This makes it very easy to see IDA in action.

You will need to uncheck Disable Turbo if you want to use your 11 IDA multiplier.
My System SpecsSystem Spec
14 Mar 2012   #7


I just saw your main problem which is common to many Dell laptops. It is called Clock Modulation throttling. This is reported by ThrottleStop in the CMod column. 25.0 means your CPU is running at approximately 25% of its designed performance level. When combined with SLFM and a reduced multiplier, it is really running like a slug.

ThrottleStop was specifically designed to cure this issue in the Dells. Put a check mark in the Clock Modulation box and set that to 100.0% and you are done. Your laptop will start working a hell of a lot better.

This has been a huge issue for so many Dell laptops. Do some Google research about throttling and clock modulation and ThrottleStop and you will soon start to uncover the mess.

Here is a huge paper which helped get to the bottom of what Dell was doing for a long, long time.

throttlegate.pdf - Google Drive

It's a huge pdf of about 24 MB written by a very smart guy that uncovered this problem. It was enough to motivate me to write ThrottleStop. :)

No one should have to suffer with a defective laptop. I am still waiting for some smart lawyer to come up with a class action lawsuit over this issue. It is crazy what Dell got away with for so many years.

When CPU-Z starts reporting multipliers like 2.0, that is a sign that clock modulation throttling is being used on your CPU to slow it down to a crawl. CPU-Z combines the reduced multiplier with the clock modulation throttling and reports an approximation of an equivalent multiplier or something like that. ThrottleStop tells you exactly what is going on once you learn how to use it.

Send me an email to the address in the ThrottleStop info box if you need more help with this.
My System SpecsSystem Spec
15 Mar 2012   #8

Windows 7 Ultimate x64

Hi, thanks for the replies!

I noticed late last night that at no point was the CPU fan spinning up when the temperature increased. So this morning I dismantled the laptop, cleaned out the fan and its outlet (finding a huge think lump of dust that was presumably preventing the fan from spinning, and which before it got stuck and blocked the fun must have been drastically reducing the cooling systems effectiveness). I also reseated the heat sink with new thermal paste. On restarting the CPU is running at normal, and at a much reduced temperature (even before it had been running hot and I'd been meaning to give it a clean at some point)

So it seems the problem was caused by the computer recognising at boot that the fan wasn't able to spin, and Windows going into what I can only guess to be a reduced performance mode in order to keep temperatures down. When I used ThrottleStop to force it to run at a higher frequency it was overheating because the fan wasn't running.

So that explains the low CPU frequency and the fact that using ThrottleStop was causing it to overheat. Fans, eh?

But aside from that, your second post was most informative. I had come across the situation where using a non-Dell charger causes the laptop to run slower, but I wasn't aware Dell were doing what you describe. Seems like a pretty bad practice, and when I eventually replace this laptop this would certainly put me off replacing it with another Dell...

So I've set ThrottleStop to prevent clock modulation throttling and I'll definitely be continuing to use the program to make sure I'm actually getting the performance I want.

Thanks very much for the help and info!
My System SpecsSystem Spec

 Intel T7250 2.0 GHz multiplier stuck at 2.0x, Core Speed at 398 MHz

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