What are differences between 4th-gen i7 M and U processors?

I know about:

  • core voltage
  • TDP
  • socket
  • price

But is there something more? Some differences like slower cache, reduced instruction set?


So, for comparison - I took two 2-core Haswell i7 processors with... same numbers - 4600M and 4600U. It may be wrong, but I couldn't find pair of M and U processors with same cache and similar clocks.

U-series is very diffrent. It's not just M-series with lower core voltage.

  • There is no PCI-express 3.0 support
  • PCI-express (2.0) only in 4x1, 2x4 modes (no 1x16)
  • USB and SATA controller is built-in
  • diffrent memory controller (supports low-power memory)
  • in some low-power devices with U-series CPU may slow down under long and heavy load (throttling, less Turbo etc.)

These are only few differences. There is a lot more, but my question seem to be not popular, so there is no reason to list them all.

My final verdict about performance differences between M and U series is:

U-series performance (per 1GHz) is same as M-series, but PCI-e limits may reduce system performance if you want to use GPU somehow (3d or as coprocessor).

|improve this answer|||||
  • 1
    Suggestion - If you had just done a bit of that research BEFORE you asked the question (say at ark.intel.com), included what you had already learned, and been specific about what confused you, you probably wouldn't have garnered any down-votes. But kudos for going and finding the answer, and then coming back to share. – Ƭᴇcʜιᴇ007 Oct 2 '14 at 13:46
  • 5
    Well, that was quite time-consuming research, I thought maybe someone else already did it and ca simple say "you can expect same CPU performance, but whole system can't be as fast as machine with M processor because of ..." – Kamil Oct 2 '14 at 14:23

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.