Thinkpads Forum

I'm still in the process of deciding for a W520 model as I've realized I do have a need for the fastest possible CPU (video rendering). I'm trying to spot one with the i7-2860QM cpu which from reading earlier posts would be the fastest (Turbo Boost up to 3.5 ghz) given that the i7-2960XM had its Turbo Boost capabilities blocked by the Lenovo design reaching only its native 2.7 ghz performance as to keep heat at safe levels.
Is this really so ?
And is this still so, no matter what BIOS upgrades have provided ?
An other thing that occurred to me: is there any i5 cpu that is more efficient than a quad core chip for single processes ?

Thanks for clarifying things,

Visitor
X201s X60s (previously T42, X31, T23)

I realized I didn't really know much about the difference between i5 and i7 either, having just automatically pulled out my wallet for the best-available-at-the-time CPU, so I googled it and found a good article here: http://www.pcmag.com/article2/0,2817,2404674,00.asp -- note that this is a recent article and focuses on Ivy Bridge CPUs not the Sandy Bridge used in the W520. I would suggest that you aim for as large a L2/L3 cache as possible to try to keep the main loop of your rendering code on-die.

I have had trouble in my W520 (i7 2820QM) with turbo boost used for extended periods of time such as rendering videos. I've stayed on the 1.36 BIOS because I have the faster RAM. I created a 99% speed power profile to disable turbo boost. Didn't really loose much overall time-to-completion because my rendering tasks are bottlenecked at the disk more than the CPU/GPU.

Intel does show 55W TDP for the i7-2960XM vs. 45W for the i7-2860QM, so I would guess that the extra heat there could easily be a problem given the same cooler design.

davidhbrown wrote:I have had trouble in my W520 (i7 2820QM) with turbo boost used for extended periods of time such as rendering videos. I've stayed on the 1.36 BIOS because I have the faster RAM. I created a 99% speed power profile to disable turbo boost. Didn't really loose much overall time-to-completion because my rendering tasks are bottlenecked at the disk more than the CPU/GPU.

Since you have faster RAM, have you tried to render the videos with Hyperthreading disabled? Somethings run faster without Hyperthreading.

jayton4 wrote:Since you have faster RAM, have you tried to render the videos with Hyperthreading disabled? Somethings run faster without Hyperthreading.

I did actually; the limiting factor was still HDD speed, so the CPU was at like 70% instead of 80% utilization. I decided to turn HT back on. Next March when I have the next video project, I may try one of those external RAID enclosures (set up with RAID 0) or maybe SSDs will be inexpensive enough to use. But honestly, I don't mind leaving the computer churning away for a few hours or even overnight while I do something else... just so long as it doesn't overheat and shut down!

So what about the W530? Does it have turbo boost disabled for the 39**XM processors or not? I'm hoping to buy one soon and noticed the description for 3920XM processor was different than the others (didn't mention "up to XXX Ghz" turbo boost verbiage).

Thanks!

davidhbrown, thanks for the link and the very interesting article. Still it is not clear to me if and when an i5 chip would do faster rendering than an i7, which i5 would that be and if we have such option in a W520 Thinkpad.
I would like to ask you a couple of questions regarding your machine model which could be an option in my case :

You mentioned about getting as much L2/L3 cache as possible and you have an i7-2820QM 2.3 ghz cpu with 8mg of L3. So for the sake of video transcodings alone, would yours be faster than a neighbouring i7-2760QM that has 6mb of L3 but a 2.4ghz cpu ? Or wouldn't it make much difference given the disk bottleneck ? (I'm considering using an SSD for the rendered videos as the bulk of it isn't too large in my workflow.)

Also, will the 2820 benefit from using the 1600mhz memory chips such as Corsair's Vengeance ? I believe the 2760 does.
Thanks again,

Visitor
X201s, X60s (previously X31, T42, T23)

i7-2960XM had its Turbo Boost capabilities blocked by the Lenovo design reaching only its native 2.7 ghz

I have not run my processor at max or near max load for long durations to see how the clock speed is affected, but I can tell you that my system does hit 3.7Ghz from time to time. I am confused. Are you saying that at high temperatures, the 2960s Turbo Boost gets disabled?