i7 2600k, i5 2500k & 2300 1155 Sandy Bridge Review Page: 1

Intel LGA1155 Review


Evolution is one of the most important things in the PC Hardware marketplace. The constant need to improve your product to be faster, more energy efficient, lower priced and more attractive to the audience is vital if you're to stay ahead in the technological war.

The real secret, the holy grail if you will, of a license to print your own money is to have something that hits the sweet-spot in ever category. If you can get a hyper-desirable product onto the marketplace at the right time, and the right cost. Probably the biggest recent examples of this are the iPhone and the Nintendo Wii Fit. Two mighty products that were instant successes and have held their value long after the initial buzz has worn off.

Back in the PC Hardware world this desirability has to come with longevity. It doesn't matter how much people want something if it's going to be obsolete in a few months, or even worse if they believe it will. The Intel LGA1156 socket, which was the value alternative to the mighty triple-channel LGA1366 had exactly these problems.

Initially coming hot on the heels of the LGA1366 Core i7s it was marketed as the more cost-effective choice. Unfortunately whilst the i7-870 is a complete nutter of a chip it was a long while before decent value chips appeared. By that point everyone had either saved up the extra for the 9 series of Core i7 Processors, moved to the Hex-Core AMDs, or heard the rumours that Intel were making a replacement for that socket.

One of the biggest benefits that AMD have is in their use of AM3 socket for many years. So you can purchase a setup safe in the knowledge you can keep upgrading for many years. The Intel Socket 775 was the last one that came from the Blue stable with a major shelf life and, thanks to its continued good performance, is still popular.

So where does this leave the recent Intel releases? The LGA1366 has been around for a while, but will soon see a replacement, and the LGA1156 has barely lasted 12 months before something new is on the scene vying for your attention. Although nobody is silly enough to expect to be future-proofed we'd at least like the ability to have something we can put one new generation of CPU in before we have to bin it off, so the new LGA1155 needs to be very good indeed to wash away some of the bitter taste that such a swift change leaves.

Technical Specifications


The i5-2300 is definitely the lower model of the bunch on test today, being 500MHz slower than the 2500K which looks like the it should be the sensible choice if Hyper-Threading isn't the be-all and end-all of your needs.

i7 2600k, i5 2500k & 2300 1155 Sandy Bridge Review Page: 2

Intel LGA1155 Review

Test Setup

Intel Core i7-2600K
Intel Core i5-2500K
Intel Core i5-2300
Intel DP67BG Motherboard
Corsair HX1200 PSU
4GB Mushkin Redline RAM
Noctua NH-D14
nVidia GTX570
Windows 7 Ultimate x64

Overclocking and Temperatures

Overclocking the new range of Intel CPUs is very different to the previous range. Previous, or currently, you have the overclocked speed of your CPU, and possibly the lower speed when the multiplier drops down in the idle state. Or at stock you had the plain speed, and then Turbo would kick in with one extra on the multiplier to give you an insignificant boost.

Now what you is overclock the multiplier that will kick in once the chip is under heavy usage. It's a slight tweak in your approach, but for stability and energy reasons it makes a lot of sense.

The main problem is that the overclock is also power dependant, and so it's vital that you open all the taps or your overclock will only go as far as it can, rather than as far as you've set it.

Core i5-2300

As the Core i5-2300 on the H67 platform doesn't support overclocking this is purely at stock, but the impressive thing is the temperatures. Barely a shift after a massive run on Prime95.

Intel LGA1155 Review     Intel LGA1155 Review  


Core i7-2600K

Boy oh boy. 5GHz. Now that's some serious speed. Unfortunately it's at 1.56v which is a little higher than we'd like to use for a 24/7 overclock, but amazingly enough it keeps ticking along at a maximum of 74°C and quite happily runs through all of our benchmarks. We'd just obviously not recommend this high voltage for a permanent overclock.

Intel LGA1155 Review     Intel LGA1155 Review


Core i5-2500K

At this point we would like to remind you that the 2500k is going to be available for around £160, and although it did need a defibrillator like 1.6v we managed to coax yet again a 5ghz completely stable overclock! Quite interestingly though not only was it stable all being cooled with a Noctua NH-D14 but it still stayed at sensible temps throughout all the benchmarks and gaming, all under 76c sensible!

  Intel LGA1155 Review  

i7 2600k, i5 2500k & 2300 1155 Sandy Bridge Review Page: 3

Intel LGA1155 Review


We'll ignore the AES comparisons as the new LGA1155 chips come complete with the AES instruction set that makes such an enormous difference, although the 2500K seems to gain by not having to split its time among virtual threads. For a couple of the tests the little Core i5-2300 keeps up with the previous Core i7s although it clearly hasn't got the grunt to push big data around such as the zLib tests.

The 2500K definitely knocks out some good scores throughout the AIDA64 tests keeping up with both the i7-870 and the i7-950.

The range-topping Core i7-2600K demonstrates its fantastic ability to perform calculations walking off with the first place in three of our tests and only bettered by the overclocked 2500K in the AES test.


The Core i5-2300 makes a mockery of its small price and mid-range status by being able to produce good memory scores. Both the stock i5-2500K and i7-2600K belie their dual-channel stature and produce results similar to the triple-channel X58. Once the overclocks kick in though the results are incredible, especially the write speeds which have been the achilles heel of the current line-up.

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Intel LGA1155 Review

SiSoft Sandra

As a test that purely tests the calculative abilities of each processor it's no great surprise to find the i5-2300 comes in last by some distance. The Core i5-2500K, which isn't that much pricier, is a much better performer managing to perform as well as the previous top-range Core i7-870 and high-end Core i7-950. Once again the overclocked capability of the i7-2600K redefine what results we expect from a Quad-Core CPU.


PC Mark Vantage

Futuremarks benchmarking suite uses a selection of in-built utilities to replicate average PC usage but in a condensed form. The switch from 45nm to 32nm and the expected performance increases show their hand here with even the i5-2300 managing to keep the numbers pumping and once we move up to the 2500K and 2600K we start to see some huge results coming in.

For pure number tasks any of these new chips would be a good choice.

i7 2600k, i5 2500k & 2300 1155 Sandy Bridge Review Page: 5

Intel LGA1155 Review


If so far we've discovered that calculating is the real pièce de résistance of the new LGA1155 chips. So it's hopefully not a big surprise to see the incredible results we're getting out of these chips. The top three test rigs on our graph are all better than we've seen from any Quad-Core, and the i7-2600K overclocked gives us the biggest score we've ever seen. For comparitive purposes a 4.5GHz Hexcore i7-980X gives only 1 point more in the CPU score than the 2600K.

Of concern is the poor results in the OpenGL tests though. If the CPU is performing as highly as it shows, then there is no reason why our GPU isn't rocking as hard as it ought.


In keeping with our results so far the wPrime95 results are stunning. 5 seconds for 32M and 173 seconds for the 1 billion place test are magnificent by anyones reckoning. We do see a huge drop off from the i5-2500K to the i5-2300.

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Intel LGA1155 Review

3D Mark Vantage

When we tested these chips on the ASUS Maximus IV Extreme, review should be live along with this one, we were amazed by the relatively poor performance of the board and chips in the 3D environment and postulated if it was symptomatic of the board itself. Considering how comparatively weak the 3D Mark Vantage results are even on this highly refined Intel board we're definitely getting a little concerned at the interaction of the various components. All the scores are consistently below those of the 45nm setups.

3D Mark 11

3D Mark 11 is a much more strenuous test of your system and yet despite using a much more theoretically modern system with an identical GPU the scores remain underneath our i7-870 and i7-950 systems. Although both the i5s could be argued as not having the hyper-threading necessary for big synthetic scores, the 5GHz i7-2600K has absolutely nothing holding it back from topping the charts by some margin.


i7 2600k, i5 2500k & 2300 1155 Sandy Bridge Review Page: 7

Intel LGA1155 Review

Crysis Warhead

Firstly we have a clear demonstration of the difference that a CPU can make, with the overclocked Core i5-2500K being 20 frames-per-second faster than the Core i5-2300. With a game like Crysis though and the power of our GTX570 all of the CPUs on test today manage to provide a perfectly playable experience.

Alien vs Predator

It definitely seems to be that when the GPU is fully loaded the P67 chipset develops a bottleneck that doesn't exist when the testing is more CPU bound. But we'll discuss this more in our conclusion. Onwards.

i7 2600k, i5 2500k & 2300 1155 Sandy Bridge Review Page: 8

Intel LGA1155 Review


So we have the replacement for the LGA1156 series of processors that just seemed to be finding their feet. With them coming it at three differing price points but not really for three different markets, we have to split this conclusion into three parts.

Core i5-2300  

The pricing difference between the two Core i5 chips is around £20 but the performance difference is comprehensive.

The Core i5-2300 definitely suffers from being the "middle" child in the SandyBridge range as it's neither so cheap as to be a bargain for the value market, nor is the performance so great that it's a genuine challenger for the top range models. The reason why we felt the need to include it is this would be perfect for a workstation machine or even a low power HTPC, the onboard GPU is perfectly powerfull enough to run HD videos with out hardly touching the main CPU itself.

Whilst gaming performance is about on a par with most things as we'd expect because we know that games are far more dependant upon the GPU than CPU alone, the 'every day' performance is sufficiently beneath the Core i5-2500K that it's incredibly tough to recommend either as a first foray into the PC owning world, and definitely not as an upgrade option.




Core i5-2500K

Moving on to the Core i5-2500K we find a definite diamond. Coming in just shy of £170 at retail it's a long way below previous top end Intel releases such as the i7-920 or i7-860, but the performance is up there with the very best. At stock it's around the speed level of the i7-950 and when overclocked it regularly takes third place in our graphs below the i7-2600K.

Although we would never recommend a 1.6v overclock, once the main vendors sort their bios out we would say this CPU is easily capable of 4.5GHz and with a bit of know how, and hopefully a decent motherboard going past this point may well be attainable with a safe 24/7 Voltage as our Intel board did droop quite badly. Id like to think a well made board with a solid power delivery would help coax more from this at much lower volts.

If you absolutely must upgrade at all times or are looking at owning an entire new PC, this is definitely the chip to have. If you've got something below the i7-950 or i7-860 then it is seriously worth a long hard look at for an upgrade.




Core i7-2600K

As we would expect from a range-topping chip the Core i7-2600K takes all the plaudits in performance terms. At stock it rocks all of our graphs, and the performance when overclocked at 5GHz is as mind-blowing as you'd expect a Quad-Core hyper-threaded 5GHz CPU to be.

Of all the things you have to consider the Hyper-threading is the most vital thing. At just short of £250 the price gap between the i7-2600K and the i5-2500K is large, especially for the normally small gap in performance. So if your tasks are largely based upon needing to make an enormous amounts of calculations in the tiniest timescale, then the extra £80 is a worthy expenditure. Otherwise, unless you must have the best at any price, we'd advise the Core i5-2500K as the best of the new breed.


Thanks to Intel for providing the CPUs for todays review. Discuss in our forums.