Latitude E6420 with Intel i7-2720QM - CPU PERFORMANCE ISSUE.

[AlAraf]

Hi,

I have just purchased Dell Latitude E6420 notebook with Intel i7-2720QM CPU. On the next day, I decided to benchmark my new notebook with PassMark Performance Test ver. 7.0 64 bit (PassMark PerformanceTest - PC benchmark software) and to compare my new "toy" with other notebooks which I was considering before the final purchase (HP, Lenovo, etc.).

Prior the tests, I updated BIOS and all other hardware to the latest firmware versions available on Dell support web page. At that time, the latest BIOS firmware version was A06. Then, I started PerformanceTest to estimate notebook performance. Finally, I downloaded benchmark results for similar notebooks with exactly the same CPU: i72720QM. At the end, I compared my notebook with Dell XPS L702X, Alienware M17XR3, Lenovo Thinkpad W520 and HP Pavilion DV7.

I was shocked when I saw result of CPU Mark score comparison.

CPU in my notebook was ca. 30% slower (CPU Mark score: 5888 points) then the same i7-2720QM in all other notebooks.

My first thought was, that some default Windows or BIOS settings reduced CPU performance, so I changed Power Profile in Windows to the best performance (min and max CPU power set to 100%). Then, I updated BIOS to the latest A07 firmware and I have changed all settings in BIOS under "Performance" tab to switch off all energy saving settings. Finally, I started PerformanceTest to repeat benchmark. Unfortunately, CPU Mark score was almost the same as before (with +/- 3% tolerance).

Then, I decided to analyze comparison benchmarks downloaded by PerformanceTest. Additionally, I downloaded results for Dell Latitude E6420 and E6520 with the same i7-2720QM CPU.

Here is what I found:

1) The notebooks form all other manufacturers like: Dell XPS L702X, Alienware M17XR3, Lenovo Thinkpad W520 and HP Pavilion DV7 have very similar CPU Mark score around 7000 - 7100 points.

2) Dell Latitude E6420 and E6520 notebooks with BIOS firmware A06 or the latest A07 have similar CPU Mark score around 5700 - 5800. It means that Dell Latitude notebooks with i7-2720QM are 30% SLOWER then competition!

3) Dell Latitude E6420 and E6520 notebooks with BIOS firmware A05 are slower "only" 10% then competition.

My final conclusion is that the latest BIOS firmware for Dell Latitude E6420 and E6520 have some kind of bug (maybe incorrectly implemented Intel Turbo Boost feature) which makes Latitude notebooks ca. 30% slower then all other notebooks with the same i7-2740QM CPU. It is quite possible, that this issue is specific for i7-2740QM CPU only. Older BIOS firmware (version A05) also have the same issue, but with less impact on CPU performance ("only" 10%).

May I ask all of you how owns Dell Latitude E6420 (and E6520) with i7-2740QM CPU and BIOS firmware A06 or newer, to replicate this results?

Please confirm if you also have the same issue and please submit the issue to Dell support. This will be a readable sign for Dell support to issue new bug
fixed BIOS firmware.

Best regards,
Adam

[AlexF]

Using BIOS A04 with Quiet (Reduced Fan Levels) mode coming back from hibernation, plugged in and docked. Switched the power profile to Ultra Performance (Max Fan Levels), but only got 4998 the first time. It never floored the CPU for some reason and the CPU fan never spun up faster than normal levels.

BUT... then I ran Prime95 torture test with 8 threads using Blended preset which floored the CPU to 100% and made the CPU temperature and fan start spinning up. Closed it, went back to PassMark, did the PassMark CPU test again now it's getting 7858, then 7717. (maybe the power profile change didn't take or not enough to trigger a power profile change? *shrug*) When doing the test, CPU-Z is showing the clock going up to 3GHz when the test is running (30x100MHz), so TurboBoost is definitely contributing.

Putting it back down to Quiet (Reduced Fan Levels) gives a 4684 CPU score and the CPU-Z shows the CPU never gets past 1.8GHz.

Still waiting for them to fix it before updating. TurboBoost definitely makes a difference. I don't know what the heck they're waiting for...

[futchi]

The new bios has bug and disable the turbo boost for 2720qm.
Use A05 or older, you will get 30% performance back.

[lennartb]

Agree with futchi, problem occurs since A06, turboboost is not working since then. A07 doesn't fix it either. It seems it only occurs with the 2720QM cpu.

Monitoring the CPU speed also shows that maximum speed is 2.2ghz. More info in the E6520 topic :-)

[AlAraf]

Dear AlexF, futchi and lennartb,

thank you for confirmation, everything is clear now. New BIOS firmware is responsible for this issue. Next pending BIOS firmware release should reclaim full i7-2720QM power, not only 20% increase which you can get by downgrade to A05 (or older) revision.

May I ask you to submit this issue to Dell? I already submited the issue for my notebook and I'm waiting for Dell reply. I hope that Dell will promptly release bug fixed BIOS, but several submissions of the same issue from different users are required.

During submission, you can paste link to this forum, to let Dell know that the issue is reported also by other users.

Best regards,
Adam

[lennartb]

Hi Adam,

Yesterday my colleague and I (we both have the same laptop) were testing with the program throttle stop. There is also a topic on the forum of this. And, I don't know how it works but it works perfect. If you set the correct values throttling works. Superpi gives a result of 11.5sec, just like with A05. (1m calculations).

It's at your own risk offcouse, but stressing the system for 2 hours did not raise any problems. It's not overclocking or something.

Just take a look at it.

Regards

[AlAraf]

Originally Posted by lennartb

Hi Adam,

Yesterday my colleague and I (we both have the same laptop) were testing with the program throttle stop. There is also a topic on the forum of this. And, I don't know how it works but it works perfect. If you set the correct values throttling works. Superpi gives a result of 11.5sec, just like with A05. (1m calculations).

It's at your own risk offcouse, but stressing the system for 2 hours did not raise any problems. It's not overclocking or something.

Just take a look at it.

Regards

Dear lennartb,

thank you for this very valuable information. It can be a good solution, especially when your notebook in no longer covered by Dell warranty. However, I'm afraid Dell can refuse warranty rights when such a change (using ThrottleStop software) will be detected in submitted to Dell user's notebook.

I strongly recommend all of you to submit this issue to Dell by as many users as possible. This is the only trigger which can lead Dell to release bug fixed BIOS firmware and will guarantee that you will keep your warranty rights.


Best regards,
Adam

[rossim80]

The problem also affects the E6520. Both A06 and A07 bioses in E6420 and E6520 notebooks with the quad core cpus are affected. The precision M4600 is also affected. this is known to dell who released a new bios (A07) which claims to solve the problem.

Dell, please solve the issue for E6420 and E6520 also!!!!

[sk8012]

There is another issue I have with E6420 (w/ i7-2720QM) with hyper threading. If hyper threading is enabled (in BIOS), then 2 cores are automatically disabled. All benchmarking tools, System info tools (CPU-Z, SIW) show only 2 cores available for use with 4 threads. This degrades performance drastically (WEI processor score 6.5, passmark CPU score 3000). The device manager shows 8 threads, but task manager shows only 4.

Disabling hyper threading solves this issue and enables all 4 cores, but only with 4 threads. The performance is back to levels specified in Adam's post.
This also appears to be another BIOS issue. Is anyone else facing similar issue?

BIOS version: A05. I tried A06 & A07 and went back to A05 for better performance.

[AlAraf]

Originally Posted by sk8012

There is another issue I have with E6420 (w/ i7-2720QM) with hyper threading. If hyper threading is enabled (in BIOS), then 2 cores are automatically disabled. All benchmarking tools, System info tools (CPU-Z, SIW) show only 2 cores available for use with 4 threads. This degrades performance drastically (WEI processor score 6.5, passmark CPU score 3000). The device manager shows 8 threads, but task manager shows only 4.

Disabling hyper threading solves this issue and enables all 4 cores, but only with 4 threads. The performance is back to levels specified in Adam's post.
This also appears to be another BIOS issue. Is anyone else facing similar issue?

BIOS version: A05. I tried A06 & A07 and went back to A05 for better performance.

Dear sk8012,

I have checked it on my notebook, however I can not reproduce the issue mentioned by you. Hyper-threading is enabled in my BIOS (ver. A07). CPU-Z, HWInfo and task manager printed correct number of cores and threads:





What value do you have under "Multi Core Support" option in BIOS? Please choose "All" and try again.

Best regards,
Adam