Thinkpads Forum

There are continual offerings on eBay of the E8435 CPU, as allegedly equivalent to the T9900. It is NOT!

While it is true that both CPUs clock at 3.06 gHz, the "E" designation indiates a TDP (total design power) of 55 watts. By contrast, the T9900 has a maximum TDP of 35 watts. The only customer for the E8435 was Apple, who used it in the Imacs. If the E8435 is installed in a laptop, it will very likely destroy the power circuitry.

I contacted one of the eBay sellers, who proudly declares himself a service veteran, but was met with extreme hostility.

Caveat Emptor!

I do not have any idea if that CPU would work in a laptop, but one small correction: TDP = Thermal design power, and is not related to any power circuitry. TDP is a measurement of the heat (in Watts) that the cooling system has to be capable of removing.

Your point is technically correct, but your correction may cloud the issue for less technical readers. The E8435 is very similar to the T9900, except that it lacks all of the power control logic of the latter. The "E" designation indicates a TDP of between 45 and 55 watts. Less technical readers may not understand that ALL of the power input to a CPU chip, or any other chip, for that matter, appears as equivalent waste heat. Therefore, TDP has a very accurate correlation with the actual power draw.

One user, not necessarily on this forum, reported the results of installing an E8435 in a Thinkpad. The machine lasted three weeks, and then "fried." Unfortunately, I can't find the post to cite.

I joined this forum for the sole purpose of commenting on this thread to say how wrong you guys are, Despite it being dead for years. There are two models of the E8435, One has a TDP of 55 watts (C0 step) while the other is 44 (E0 step). I can't testify to the 55 watt processor variant, however i personally installed the 44 watt version my in asus g51 and for over 2 years now runs better than ever, and since i knew i was nearly doubling the TDP from the prior processor that came with the laptop (p8700) i disabled the fan speed sensor just to be sure, and as it turns out the laptop runs cooler than it did right out of the box.

With that said, i can obviously see people having trouble using this processor in their laptop if it wasn't meant to take such a power hungry processor.

But frankly, if you are changing out the processor in your laptop and it blows up in your face, you kinda deserve it.

Not in theory but the processor would work the same. Without quality thermal paste and an upgraded heatsink and or fan. A person could have problems with the higher powered processor most likely intended for a desktop computer. If a processor is the correct socket type, you can use whatever processor you want. Issues such as the motherboard not recognizing the CPU could result.

Obviously with weak cooling and not monitoring heat via an app like Core Temp could result in overheating. I do question if people spend any time watching CPU-Z with the fluctuations in CPU speed and voltage. This is why I don't think processor speed matters much within a specific class of processor. This would mean i3,i5,i7 within the same generation of processor do not make a significant difference between say 2.4ghz and 2.8ghz within the same model line say i5 of the Sandy Bridge, Ivy Bridge, Haswell family.

If you run a processor in power save mode, even a desktop processor would not overheat in a laptop. Years ago people used to put desktop processors in laptops mostly compromising the battery life significantly.

FWIW...

I've ran this CPU (E8435) in R500 for a couple of months with no ill effects to observe. Yes, it was on the warm side of the spectrum. No, it hasn't caused any issues that I could detect.

As with most things in life, YMMV...