I want to upgrade the CPU of an old computer I have(CPU in it being an Intel Core2 Duo E8400 3.0Ghz). I’ve looked in the motherboard manual to see wich CPU are compatible with it. Since there’s is a few options I’ve looked the benchmark of some of them on the passmark website. The current CPU installed in the computer is a 3.0 Ghz dual core and has an average CPU mark of 2154.

I’ve looked 2 options for the upgrade:

  • Intel Core2 Quad Q9300 2.5Ghz quad core with an average benchmark of 3163 (CPU released in Q4 2008)

  • Intel Core2 Quad Q8400 2.66Ghz quad core with an average benchmark of 3176 (CPU released in Q4 2009)

Of course the second option seems better than the first one, but I’m still worrying about the Ghz, since the current CPU installed in the computer is 3.0Ghz and these 2 options have lower Ghz than the current installed one,but more core.

I want to have higher computer performance, so should worry about the lower Ghz, or it doesnt matter since they both have more cores?

closed as off-topic by JakeGould, Ramhound, n8te, robinCTS, music2myear Jul 16 '18 at 20:07

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  • First, sadly this question should be closed because the choices are too broad and too opinion based. That said, without knowing what you want to do or what your motherboard can handle, CPU speed is silly at best. Tons of other factors affect speed on modern systems and it is utterly all dependent on purpose of the system and what you expect it to do. My recommendation is get the best upgrade you can afford. Don’t penny pinch if you care about the system. But again, who knows if your current CPU is fine for your purposes and something else—like storage—should be upgraded. – JakeGould Jul 14 '18 at 23:56
  • This is a 10 year old system so you can look at the benchmarks and get a very good idea of the relative capabilities. You will not notice any difference between those two upgrades but either will be significantly better than what you have. I don't see how this is being seen as an opinion by some. The fact that going from HDD to SDD will be a bigger system speed improvement is only a distraction because it isn't what is being asked. – krowe Jul 15 '18 at 0:02
  • You might get better answers if you provide more information - like CPU model numbers and system purpose. – davidgo Jul 15 '18 at 0:04
  • @JakeGould ive checked in the motherboard manual to check only cpus who are compatible according to the manual. The hard drive of that computer has been replaced about 1 year ago for a standard SATA III 5400rpm one so I dont think the hard drive is really causing problems here. I updated my post with CPUs brands and models if that can help – William Weifenbach Jul 15 '18 at 0:35
  • @davidgo updated the post with CPUs models and brands name – William Weifenbach Jul 15 '18 at 0:38

According to what you wrote, both new CPUs have the same number of cores, and the performance is nearly the same - based on the information provided the performance will be pretty much the same. You will likely find the newer of the 2 CPUs will use slightly less power.

For a typical computer workload you will find the newer CPUs will outperform the old one, but there will be some jobs - where the older computer will do better (those jobs where the system is performing a single workload which can't be split up)

  • ark.intel.com/compare/42112,42112,33922,33910 will compare your 3 CPUs. There is virtually no difference between them, but the Q9300 has a couple of slight advantages - It has Intel trusted Execution technology which could be useful if running VMs , combined with a 6 mb cache - however it comes at a 30 watt power premium. If you factor in the cost of power consumption of these CPUs and very limited performance of these CPUs, you would probably (over time) be better off getting a newer CPU+Motherboard combo. – davidgo Jul 15 '18 at 0:52
  • Thank you for your reply. I have upgraded the question with the CPU brands and models Im talking about if that can help – William Weifenbach Jul 15 '18 at 0:53
  • I dont really mind about power consumption cost, I just want better performance. I see the Q8400S has 4mb cache instead of 6mb cache; will this have impact on performance or its nothing to worry about? And I dont run VM's. Also this is a bit of an off topic question but can I use the same heatsink thats actually in the computer and use it with the new CPU im going to get? Or it needs to be "compatible" or needs to fit some certain specs of the new CPU? – William Weifenbach Jul 15 '18 at 2:09
  • Is Intel trusted Execution technology necessarily an advantage? See theregister.co.uk/2017/11/20/intel_flags_firmware_flaws – DrMoishe Pippik Jul 15 '18 at 2:15
  • You will get better performance, but in the overall scheme of things the performance increase will probably be very modest at best. More cache will give you better performance, but,of-course, the Q8400S has a faster clockspeed that would seem to offset that. I imagine you can use your existing heatsink, provided you know how to reapply it properly. Are you sure the bottleneck is your CPU, and not your hard drive? In the general case, I would expect an SSD to make a way bigger performance impact then a new CPU. – davidgo Jul 15 '18 at 2:15

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