The base model Surface Pro 3 features the Intel Core i3-4020Y, which has two cores clocked at 1.5GHz, no Turbo mode, and an Intel HD4200 GPU which seems a bit underpowered for such a high-res display, but we'll have to wait and see how it performs. The mid-range model has an i5-4300U, which is what we expected. It features two cores clocked at 1.9GHz with Turbo mode that can reach 2.9GHz, and the Intel HD4400 GPU which is the same GPU as in the Surface Pro 2. The top of the line model has the i7-4650U which offers two cores clocked at 1.7GHz but with Turbo mode up to 3.3GHz, and the Intel HD5000 GPU.
While performance will be a bit slower on the lower range processors, it shouldn't be a problem overall. Microsoft engineers told ZDNet that the i3 model can power two external displays running at 1920x1200@60FPS, and the i5 and i7 models should be able to handle two external monitors running at 2880x1800@60FPS. All of this while still having the built-in touchscreen fully functional. That is pretty impressive.