Thinkpads Forum

FYI .... the new 25W P9500 2.53 Processor is now being offered as an option on custom configured W500 units on Lenovo's U.S. university program sites.

Wondering how much this 25W processor will improve W500 battery life?

One would guess 29%.

You are going to get the best power saving by going from the 6MB 35W chips to a 3MB 25W chips. The vast majority of the power consumption in those chips is in the L2 cache.

Paul386 wrote:One would guess 29%.

You are going to get the best power saving by going from the 6MB 35W chips to a 3MB 25W chips. The vast majority of the power consumption in those chips is in the L2 cache.

I believe the 25W P9500 has 6MB L2 cache ..... I don't see an 3MB cache version (yet).

I wonder what and where is the performance hit by moving down to 3MB L2 cache?

eecon wrote:

Paul386 wrote:One would guess 29%.

You are going to get the best power saving by going from the 6MB 35W chips to a 3MB 25W chips. The vast majority of the power consumption in those chips is in the L2 cache.

I believe the 25W P9500 has 6MB L2 cache ..... I don't see an 3MB cache version (yet).

I wonder what and where is the performance hit by moving down to 3MB L2 cache?

The P8600 is 2.40Ghz / 3MB L2 / 1066Mhz FSB / 25W

http://www.newegg.com/Product/Product.a ... 6819111009

The performance hit from the decreased L2 cache might be at most 5% (4MB Core 2 was about 3.5% faster than 2MB Core 2), but the power savings will be 20-40%.

Reference this article for 2MB versus 4MB

http://www.anandtech.com/cpuchipsets/in ... i=2795&p=4

I do not get it really. The P9500 is 6MBytes L2, and has a TDP of 25 Watt. So that can not really be the L2 cache, or do I miss something here?

cheers

freakwave wrote:I do not get it really. The P9500 is 6MBytes L2, and has a TDP of 25 Watt. So that can not really be the L2 cache, or do I miss something here?

cheers

The TDP rating is not its power consumption but rather its maximum cooling requires. OEM's must provide enough heatsinks to dissipate 25W of power.

This does not mean it will ever consume that much power. For example, the Core 2 Duo E8XXX series are 65W TDP but never really go over 30W consumption.

Also I believe the cache is always consuming power at the max rate while the cpu power consumption rate varies depening on the load ?

Not at all true. On the latest Core2 models, the caches have extensive power management. In fact, in the lowest power down state, the L2 cache is emptied and turned off. This can happen in less that 1/10 of a second.

What is the diference in terms of performance between the T9400 and the P9500. In Europe the P9500 is much cheaper than the T9400 and more availbale, but in the US is the other way around... Is the only diference the fact that the P9500 runs cooler than the T9400? I'll be using it mainly for Autocad and for some Photoshop and would like to know which one works best...

Possibly a few percent. The P9500 should be a more expensive chip as a "top-bin" grade. (fastest for the TDP). Perhaps some European energy incentives or taxes change things. I think it is almost always a better choice if the price is the same as the T9400.