Thinkpads Forum

Hello everyone,

We were purchasing the T400 (2767-R3U) which has Intel's T9400 2.53GHz processor. Now we are about to pick a T410 model. However there is a debate here at my company on how the T9400 2.53GHz processor compares to the new i5-520M 2.40GHz processor.

One camp says we are okay choosing i5-520M because, despite the GHz number, it really is faster than the old T9400.

The other camp says we have to go with the faster i5-540M 2.53GHz processor because that would be the same as the T9400.

Do any of you guys know the difference between these three processors, or where I can find a comparison?

T9400 = 2.53 GHz
i5-520M = 2.40GHz (but is newer and might actually be faster than T9400)
i5-540M = 2.53 GHz

Thanks in advance.

Loof

Thanks a.b.e. that is an interesting link and shows that the i5-520M is better than the T9400. But it also shows the i5-520M as better than the i5-540M, which doesn't quite make sense.

Anyone else have insight on this?

Thanks all.

Loof

Loof wrote:Thanks a.b.e. that is an interesting link and shows that the i5-520M is better than the T9400. But it also shows the i5-520M as better than the i5-540M, which doesn't quite make sense.

Anyone else have insight on this?

Thanks all.

Loof

My guess is it's a quirk of the test. Both the 520M and 540M are 35W TDP units. It's a bit complex to explain, but the way the Intel Turbo Boost works is that it can dynamically temporarily overclock one of the two cores while basically shutting the other one down if the current demand on the system demands a lot from a single thread of execution at that point in time rather than multiple. What can limit this is the current power consumption of the entire die, which cannot exceed 35W. Because the 520M has a lower clock speed, it consumes a bit less power and may actually have a bit more "headroom" (unused TDP) which allows it to turbo boost slightly more than the 540M doing the exact same tasks.

I'm not too familiar with the particular benchmark they're using in that chart, but the synthetic task(s) in the benchmark may lend themselves to this odd quirk. In terms of real-life performance outside of synthetic benchmarks, those two CPUs are going to perform very closely in terms of performance and power consumption, with the 540M generally having a slight lead over the 520M in performance, and the opposite in power consumption.

Does this help at all?