I am planning to build a computer and my first problem was the processor. I saw many options on the market and am interested in choosing between these two. I'm thinking on choosing the i3 because it's part of the generation of 'i series', but someone told me to look for it's clock speed which is 'GHz'.

Now I am uncertain of which to purchase.

  • You should precise a bit which P4 and i3 (the complete reference) you are considering. Adding what you are planning to do with it would be great too. As a starting answer, do not consider Ghz as "greater is better". It is true on the same processor but since CPUs can be very different, it's far to be the only thing to consider.
    – comicurus
    Jul 12, 2016 at 8:51
  • @comicurus Intel Pentium 4 Processor 2.80GHz 533 MHz 512KB Cache | Intel Core i3 4005U Processor 1.70GHz 3MB Cache
    – KentZ
    Jul 12, 2016 at 8:58
  • 1
    You'd better add these precisions by editing your post ;)
    – comicurus
    Jul 12, 2016 at 9:14

2 Answers 2


The answer is quite straightforward: P4 has only one core, 512kb L2 cache vs 2 cores and 3MB cache. These two caracteristics have to be considered as much as clock speed.

Besides, P4 is manufactured with 120nm vs 22nm => P4 uses 68.4W while i3 uses 15W.

The P4 is quite old now so you also have to consider that its old socket isn't available on newly main-boards (no ddr3, no usb3 etc.)

  • 1
    The i3 in question is many, many times faster than the P4. While a P4 may have, at most, two threads, the i3 enjoys double that number (4), and on top of that it performs many more instructions per clock than a P4, negating its clock speed advantage. The P4 also lacks many modern instruction sets, which can make it difficult to run modern software. Get the i3 as comicurus implies.
    – Adam Wykes
    Jul 13, 2016 at 4:03
  • To put this into context, you may want to add in passmark benchmarks. The i3 4005U is rated at 2453 overall (959 single threaded), while the P4 2.8Ghz is rated 325 (628). Even the highest end Pentium 4's are slow in comparison to the slowest i3, the 3.8GHz P4 is rated 490 (822) for example.
    – Mark Booth
    Jul 16, 2016 at 22:26



Clock speed ('Ghz') is not all that matters when it comes to performance.

Quite a few things can dictate how well a certain CPU performs, including but not limited to

  • IPC (instructions per cycle)
  • Arcithecture ('nm')
  • Clock speed ('Ghz')
  • Cache ('MB' & 'KB')
  • Cores (1,2,4,6,8,etc.) (multi thread performance)
  • TDP ('W','Watts') (Power consumption)


Furthermore, a CPU's desirability can furthermore be increased/decreased by how many features it has and what chipset it uses.

  • Hyperthreading (Virtual cores)
  • RAM capacity
  • RAM channels (Complicated stuff, not too much to worry about)
  • Chipset (Does it support modern motherboards?)
  • Integrated graphics (does not require a separate graphics card)



  • i3-4005U
  • Pentium 4 2.8Ghz
  • i3 uses 22nm architecture, P4 uses 120nm
  • i3 has a 15W TDP, P4 has a 65W TDP
  • i3 has integrated graphics
  • i3 has hyperthreading
  • i3 has 2 cores, P4 has 1 core
  • i3 has a newer chipset
  • i3 has a built in memory controller
  • i3 has more cache
  • i3 has a variety of features the P4 doesn't


(i3 on the left, P4 on the right) (Higher is better!)

  • Passmark | 2435 | 325 | i3-4005U is 650% better.

Unfortunately there are no other benchmarks that I can find that contain information on both the i3-4005U and the Pentium 4 since the Pentium 4 is 11 years older than the i3.


Get the i3-4005U because it is far less outdated, requires no dedicated graphics card, uses a less outdated chipset, and performs much better in terms of single core performance and (because it has a second core) dual core performance.

  • Do not mixup things, the 'nm' doesn't give you the CPU's architecture. One architecture could be manufactured in several thickness. Otherwise good answer ;)
    – comicurus
    Jul 15, 2016 at 6:33

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