Thinkpads Forum

I have a T400 6473-PUG and I'm planning to upgrade the CPU. Currently it has a Intel® Core™2 Duo P8400 2,26 GHz and I want suggestions on a new CPU.

I have that same CPU on my R500. Got a T9400, which has double the L2 cache, should be a nice boost.

I'd put a T9600 in it.

I have found a SLG9F (T9600, 2,8 GHz, 6MB cache) with socket P. Will that work?

According to; https://www.thinkwiki.org/wiki/Category:T400, the T9600 is among the available CPU options.
The T9700, T9800, and T9900 will also work, but they're usually too expensive for the performance increase they offer. They also run hotter.

I bought a T9600 which made a difference and with doubled RAM size and Linux Mint it became a real nice machine.

Nice work. I have a T400 with T9600 as well and it is snappy, capable of YouTube 1080 60 as the sole task or lower res with multitasking. The Core 2 Duo era is not dead and with a non-whtelist BIOS you can hypothetically even install a Wifi 6 card, if that takes over....

TPFanatic wrote: ↑

Thu Mar 16, 2023 6:33 pm

Nice work. I have a T400 with T9600 as well and it is snappy, capable of YouTube 1080 60 as the sole task or lower res with multitasking. The Core 2 Duo era is not dead and with a non-whtelist BIOS you can hypothetically even install a Wifi 6 card, if that takes over....

Hi I just wrote a post about a swap to a t9600 on my t400, did you ever have a problem with the CPU getting stuck at 1.6ghz? Any insight would be appreciated

I have a spare P9600 and T9900 on hand, P9600 is one step down of the top dog 25W P9700 and T9900 is the top dog. But you can imagine the T9900 is not going to be cheap... And since T400 shamefully only has room internally for a 4 cell battery (6 and 9 cell are all protruding ones), and trust me you really don't wanna count on a Chinese aftermarket 4 cell battery in 4S1P configuration - the internal resistance of those Chinese cells without any cells in parallel is going to harm its reliability massively, sticking to a P series is probably a better idea...

I had P8600 and upgraded with P9600. I'd say this is the best option for T400 to my mind. P is on par with T (or even superior in some cases) but has a significant advantage - it is considerably cooler and quieter due to its TDP of only 25 vs 35 on T. The Performance of P9600 is equal or superior to some early i3s which suits me fine. Yes, there's also P9700 with 4% performance increase but at the cost 12% TDP increase (28 not 25 as someone mentioned above)? It's quite doubtful. So P9600 remains the top one with low 25 Watt.

this computer here t400 has now t9900 it runs well alot cooler than the t60 which is nice, even with better cpu.