Core i7 2600k vs i5 2500k vs Phenom 955BE

Posted: February 13, 2011 in Hardware

This is what happen in my mind for awhile now and thank God, the Sandy Bridge SATA issue save me for a while from making pretty tough decision.
However, since I already made the chart, I think it is nice to share with the world.

I am using Phenom 955BE right now and I am wondering either i7 2600k is a worth upgrade. If the answer is yes, how about i5 2500k. Although it doesn’t has the additional (HT) 4 threads, in most benchmarks it performs pretty well compare to his bigger sibling. And don’t forget, it is also significantly cheaper than i7 2600k too. So, if I take price into account, which one has more performance per money?

So, I fire up Microsoft Excell, get performance data from CPU chart and include current price for all the three CPUs, here are the outcome.

Chart 1: Relative Performance. Normalize to 100%

The graph above shows relative performance for each processor compare to the one that score the highest. This graph could be read from different angle. But personally I prefer to read it this way. If i7 get 100%, i5 get 75% and Phenom get 50% for benchmark A, it mean, i7 is 50% faster than i5 and 100% faster than Phenom 955BE. Otherwise, it could be read, Phenom 955BE only has half i7 power and i5 has only 3 quarters of i7 power. These number (in my explanation is just an example, regarding on how to read the graph. For actual number, please refer to table 1 (below).

Chart 2: Performance over Price

This graph (above) shows these CPU’s relative performance vs their own price. The one that has highest performance over price ratio, get 100%.

Chart 3: Performance vs Price (i7 vs i5 only)

Same as second graph but without Phenom 955 BE. A bit easier to compare which one has more bang for bucks between i7 and i5.

i7 2600k definitely has significant performance advantage over i5 2500k as shown in graph 1. However, if we consider i7 and i5 price, i5 has better performance per money as shown in graph 3. Interestingly, the most sensible purchase is Phenom 955BE (for performance over money : comparison of this trio). So, if you want the best of the best, rest assure that i7 is fast enough to differentiate its status compare to i5. However, if ultimate performance is not your aim, but you look for balance and sensible purchase, i5 is your best bet. Last but not least, if you plan to buy Phenom 955BE, I am happy to report that you gonna get most from your money.

As for my case, I might on hold my i7 2600k purchase until Intel solve P67 chipset issue. Its performance for multi-threading applications (where I expect more and more aps in the future will support more than 4 threads) + I am moving from 4 threads to 8 threads processor, give me enough reason to purchase i7 2600k. Graph 4 shows what I will gain if I upgrade my Phenom 955BE to i7 2600k. (This graph doesn’t take price into account)

Thank you.

Table 1: Raw Score

Table 2: Convert ‘less is better’ to normalize score=

Table 1: Performance Over Price (Normalize to 100)

  1. West says:

    Thank you for you work (as well as data sources for their work too), the way you compare and visualize the results of comparison is very good and reasonable. I agree i5 is a good choice until you require the top performance possible being ready to pay extra money for it.

  2. jonap says:

    comparing $150 955BE with $340 2600k ??

    i know intel processors are better, but this comparison is ridiculous..

  3. James says:

    Thank you for making this comparison! Obviously the more expensive is better in this case, but I currently have a Phenom II that I’ve unlocked to the quad core, so it’s nice to see that it is DEF worth me buying the i7 from my current 955BE!

    Thank you

  4. expertester says:


    yep, that is the reason why i do this comparison. As i explain in this post, I own 955BE and wondering if it worth to upgrade from 955BE to i7 2600k. That is why, there is a chart that normalize performance / price where 955BE beat i7 and i5 significantly.

    The idea of this post is to help me on deciding; to buy or not to buy i7 2600k. Is the performance advantage worth the money or Phenom 955BE is still enough.

  5. Ace says:

    Yeah I’m in the same situation. I have my 955 at 4Ghz quite happily but keep wondering about a 2600k or maybe a 2500k. I kinda want an 8 core CPU and wish ivy bridge would hurry up and allow that on 1155 but it seems the only 8 core Intel CPU’s will be on 2011. Really though until AMD Bulldozer comes out the best path wont be clear. Maybe Intel will drop the 2600k’s price to be competitive with AMD’s Bulldozer. Interestingly enough providing AMD release Bulldozer AM3 pin compliant it should work in any AM2/AM2+/AM3 motherboard with a simple unofficial bios CPU microcode mod. All we do is take the microcode from another ROM we know supports the CPU and use CBROM to reintegrate it back into our old ROM. Anyhoo I may post back here in July after Bulldozer comes out, peace.

  6. expertester says:

    Although I already bought i7 2600k, I sincerely hope that AMD Bulldozer could kick i7 arse for the sake of healthy competition. Hence, the evolution of processor will become faster or at least will make the price in check.

    It is great to know what our phenom mobo could still be used for Bulldozer with a mod bios. Always love AMD for their price aggressiveness.

    • Ace says:

      Yeah you can’t beat AMD at their low end price points. In the end I caved and got a 2600k + P8P67-Pro + 1.35v 8-8-8-24 G.Skill ECO 2x4GB 8GB Kit. I figure sure the 2600k is expensive but i have a sneaky suspicion 8 bulldozer cores will match 4 sandy bridge cores but as overall gflops and single thread will suffer as always. At least with a 2600k it should rip through stuff like a ninja and in late 2012 I can grab a nice energy efficient ivy bridge 6 or 8 core cpu with that 3d transistor tech. If ivy fails to produce 6 or 8 core cpu’s to my liking il just upgrade to haswell the year after. We already know roughly how its going to go for amd in 2012 and we are to expect 10 core enhanced bulldozers which should maybe beat hyperthreadless 6 core ivy bridge. On the flipside though I am still going to choose amd for my next netbook as the ulv quad core zacate comes out also in 2012.

      The 2600k has not arrived yet and is not due till monday but I keep getting weird feelings like ive made the wrong decision and perhaps my 955BE would have sufficed. Idk but i’ve got a feeling once I get the 2600k and its all set up il feel fine. šŸ˜›

      • Doct0r says:

        Did you find a significant increase in speed to justify the cost?

      • Ace says:

        Oh yes! Had my 2600k for some time now. (Well actually its my 2nd)
        1st one lasted 3 weeks at 1.44v 4.8ghz before giving me constant BSOD’s.
        2nd one still going happy at 4.4ghz 1.24v and even beats gflop scores of
        other 2600k’s clocked higher.
        Tbh this chip is pretty incredible compared to the 955. Its the big things and the little things.
        Big thing: GTA4 and every other game runs uber smooth now.
        Little thing: stuff like onscreen animated gifs/videos dont do that weird random laggy thing.
        Big thing: on cinebench 11.5 i get 8.75.
        Little thing: hyperthreading yes it really does help.
        Big thing: Power consumption (of lack of) 3.4w idle!
        Little thing: no more fixed manual volting up and down like on my old amd board that never quite handled the am3 bios update.

        Overall tho id say if you are reading this then you perhaps have an AMD rig and are wondering if to wait for bulldozer or go intel? Well ive seen the official AMD benches of bulldozer and its like this:

        8 core Bulldozer at 4.2Ghz scores about the same as a 2600k at 3.8Ghz in cinebench 11.5. But the IPC speed/single thread speed is half of the 2600k but the physical thread count is double. The 2600k uses 80w (exc IGP) and the Bulldozer 125w at stock.

        Bulldozer good for people who encode video/multithreaded tasks and need budget throughput.

        2600k best for people who need IPC superiority/single thread speed/benchmarkers/gamers and power conscious people.

        There is a possibility that I have wondered about tho. You could interleave every other core on an 8 core bulldozer chip so that each module does not have to share resources and works like a normal core. With the other module sub cores disabled it may allow some thermal headroom and allow you to over clock the remaining 4 cores to higher levels. Now possibly if you could get it past 5.5Ghz+ ul be almost approaching the IGP speed of a stock 2600k maybe.

      • expertester says:

        Wow, very well said. For those who are pretty confuse about IPC, it is instruction per cycle. The higher the better (efficiency).

  7. st3pp3r says:

    Bulldozer coming out soon ? any idea on pricing ?

  8. Kay says:

    YES approx. 10% speed diff for i7 over i5 duals… Quads can have up to 40% more in serious multitasking ability. Yet i5 still more bang for buck. I7 coming down in price so i7 best buy very soon… Followed by quad i7 will be most main stream later in year. Go Dual i7 or Quad if u got the backs as not a huge amount extra for i7… Serious budget conscious can get great 2nd laptop deals for i3 and i7 at say 60% off prices 1 year ago.

    Buy i5 now As New and it 60% down in a year also. I7 maybe 40% as next generation out later in year.

    All are fine for Windows 8… I have dual i7 for Mac, windows 8 beta and windows 7 triple boot. As a tech l support these OS… So Dual great for now and future. Who knows after 2014… Depends if we get a quantum leap in computing- doubt it as commercially baby steps makes most money for us all.

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