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CPU upgrade on T400
CPU upgrade on T400
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.
Thinkpad addict since 1998.
Re: CPU upgrade on T400
I have that same CPU on my R500. Got a T9400, which has double the L2 cache, should be a nice boost.
Thinkpads
R51 1829-W1C 2GB RAM
R500 2716-RY6 8GB RAM
T520i 4239-47U, 16GB RAM
T530 RIP
P15 G2 20YR 16GB RAM
SK-8835 Ultranav keyboard Japanese layout
R51 1829-W1C 2GB RAM
R500 2716-RY6 8GB RAM
T520i 4239-47U, 16GB RAM
T530 RIP
P15 G2 20YR 16GB RAM
SK-8835 Ultranav keyboard Japanese layout
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axur-delmeria
- Senior ThinkPadder

- Posts: 4413
- Joined: Mon May 28, 2012 5:49 am
- Location: Metro Manila, Philippines
Re: CPU upgrade on T400
I'd put a T9600 in it.
Planned Purchase: T480s i5-8350 FHD Touch
Impulse Buy: Thinkpad not named for safety reasons
RIP: X220 4291-C91 X61 7676-A24 760XD-U9E
Impulse Buy: Thinkpad not named for safety reasons
RIP: X220 4291-C91 X61 7676-A24 760XD-U9E
Re: CPU upgrade on T400
I have found a SLG9F (T9600, 2,8 GHz, 6MB cache) with socket P. Will that work?
Thinkpad addict since 1998.
-
axur-delmeria
- Senior ThinkPadder

- Posts: 4413
- Joined: Mon May 28, 2012 5:49 am
- Location: Metro Manila, Philippines
Re: CPU upgrade on T400
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.
The T9700, T9800, and T9900 will also work, but they're usually too expensive for the performance increase they offer. They also run hotter.
Planned Purchase: T480s i5-8350 FHD Touch
Impulse Buy: Thinkpad not named for safety reasons
RIP: X220 4291-C91 X61 7676-A24 760XD-U9E
Impulse Buy: Thinkpad not named for safety reasons
RIP: X220 4291-C91 X61 7676-A24 760XD-U9E
Re: CPU upgrade on T400
I bought a T9600 which made a difference and with doubled RAM size and Linux Mint it became a real nice machine.
Thinkpad addict since 1998.
Re: CPU upgrade on T400
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....
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Registry Tweak To Enable 2 Finger Scroll On Old Synaptics Touchpads
Registry Tweak To Enable 2 Finger Scroll On Old Synaptics Touchpads
Re: CPU upgrade on T400
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 appreciatedTPFanatic wrote: ↑Thu Mar 16, 2023 6:33 pmNice 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....

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kfzhu1229
- Senior ThinkPadder

- Posts: 2659
- Joined: Tue Sep 22, 2015 10:59 pm
- Location: Toronto, Canada
Re: CPU upgrade on T400
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...
Dell Lat CP MMX-233 64mb 40gb W2k
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)
600 PII-266 416mb 40gb WXP
T23 PIII 1.13ghz 1gb W7
Precision M4300 X9000 8gb 160gb WUXGA Ultrasharp fp W10
T530i 15.6" i7 16gb fp W10
UXGA:
A30p PIII 1.2 1gb W7 (IDTech)
T43p 2.26 2gb fp W10 (Sharp)
Lat C840 P4-2.5 2gb 60gb W7 (Ultrasharp)
Re: CPU upgrade on T400
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.
T400 P9600 8Gb/480 SSD/Hybrid graphics/WXGA+
Re: CPU upgrade on T400
this computer here t400 has now t9900 it runs well alot cooler than the t60 which is nice, even with better cpu.
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