Intel Core i5 750 – First Look


Intel Core i5 LogoIntel took a big leap forward in the design department when it launched Core i7 900-series processors last year. Just a few of these improvements included a new triple-channel memory controller integrated into the chip, a new QuickPath Interconnect system to replace (and improve upon) the front-side bus architecture of old and the return of hyperthreading that split the chip’s four physical cores into eight virtual cores for increased system performance.

The Core i7 900-series chips were based on a new Intel X58 chipset and LGA1366 socket, therefore aspiring enthusiasts had to invest in new motherboards to reap the benefits of the Core i7 900-series platform. This rig was also expensive, so Intel recently launched a more mainstream processor – the Core i5.

The Core i5

The new Intel Core i5 750 is the first release in a series of processors based on a mainstream version of the Core i7 platform. It is a quad-core part based on the “Lynnfield” architecture, fabricated using a 45nm process ( Intel’s newest processor architecture known as Nehalem) and utilizes the new LGA1156 platform (note: Different from the Core i7’s LGA 1366). The Core i5 750 CPU is set to cost around the Rs. 16,000 mark and will operate at a 2.66GHz speed. It will feature a whopping 8MB L3 cache, but no Hyper-Threading support will be present.

Like the i7, the Core i5 CPU also run on Intel’s latest P55 chipset, which necessitates a new motherboard purchase for use. What’s changed, however, is that the Core i5 CPUs has adopted a different permutations of the fanciest of the Core i7 900-series’ features.

Core i5

What has been dropped

To make it more economical Intel has removed the QuickPath Interconnect and triple-channel memory controller and replaced it with a Direct Media Interface (DMI) and dual-channel memory controller. The difference is that QPI is like hyper transport with bandwidth of 25.6GB/s. It is the new “front side bus” being a direct link from the CPU(s) to the north bridge. DMI on the other hand is a connection between the north bridge and the south bridge with bandwidth of 2-4 GB/s. Does it matter? Not much. Most software don’t require such heavy power just yet offered by QPI and given the minute performance differences between current dual- and triple-channel memory configurations this is not much of a loss. This is however bad for future proofing. If you were to go out, and buy an Core i5 rig right now, a year down the road, when prices drop and you’d like to purchase the i7, you’ll have to buy another motherboard and new ram from scratch. It is not designed with the upgrade consumer in mind. But even remaining on the same platform means plenty of options such as future offerings including the 32nm Clarkdale Core i5 processors that will have a thermal design power of just 73 watts, 23% less than that of the 45nm Lynnfield architecture. Also meant to use the same platform are the Core i3 series and let’s not forget the Core i7 800 series.

Secondly, an integrated PCI Express graphics controller on this Lynnfield CPUs can either deliver 16 lanes of bandwidth to a single PCI Express 2.0 videocard or split this connection into two x8 lanes for an SLI or CrossFire setup. Although it’s a cut from the full 32 lanes (for a dual 16x or quad-8x configuration) provided by Core i7’s X58 chipset, the bandwidth reduction should only affect those who SLI or CrossFire dual-GPU videocards.

Third, like we mentioned earlier, the core i5 has no hyper-threading. While Core i7 is a quad-core, it appears in Windows as having eight cores. This further improves performance when using programs that make good use of multi-threading. Core i5 products, however, will not have this feature, which means operating systems will recognize the processors as having four core and no more. This will have no affect on the performance of most applications, like web browsers and even games, but it will be a blow to those who use 3D rendering software and other such programs that excel with multi-threading.
Performance

For the most part, the Core i5’s internal workings are identical to existing Core i7 processor and offsetting the superficially dumbed down feature set is a more aggressive implementation of Intel’s auto-overclocking feature known as Turbo Boost. Whilst the Core i7 900-series CPUs will only increase their multipliers to a maximum of two additional steps according to system demands (effectively taking a 3.33-GHz processor to 3.6-GHz depending on how many cores are in use), the new Lynnfield Core i5 750 processors are able to jump up four multiplier steps (2.66-GHz to a maximum 3.2-GHz) with Turbo Boost enabled. With over-clocking you can easily expect to hit the 3.6 GHz mark and even up to 4.3 GHz if you know how to. This chip has a lot of room to spare.

Our Test

Instead of using a high-end system, we decided to put the Intel Core i5 750 to the test using a real-world system that mostly anyone can afford and running just a gaming test for lack of other options.

System Configuration:

Manufacturer: Intel
Family: Intel(R) Core(TM) i5 CPU 750 @ 2.67GHz
Architecture: 64-bit
MultiCore: 4 Processor Cores
Capabilities: MMX, CMov, RDTSC, SSE, SSE2, SSE3, PAE, NX, SSSE3, SSE4.1, SSE4.2
Cache
Level 3, 8 MB
Level 2, 256 KB
Level 1, 32 KB

Graphics Card: 1GB PCIe NVIDIA GeForce 9800 GT (Microsoft Corporation – WDDM v1.1)
DirectX Info: Version 10.1
RAM: 2 GB DDR2

Test Results

Core i5 Specs

Benchmark Results

3D Mark Advantage Specs Core i5

Checking the scores online shows that the Core i5 750’s score of 12624 falls right around the scores set by competing PCs that use Core i7 920 processors and is better than the scores set by the Core 2 Duos and most of the Core 2 Quads of the world.

CPU Test 1 Score: 1794.93 Plans / sec

AI: The AI test features a high-intensity workload of co-operative maneuvering and path-finding artificial intelligence calculations. The test setting is an airplane race course crowded with planes, all attempting to navigate through a series of gates while avoiding collisions with each other and the ground. The test load consists of the movement planning for each airplane. The workload is entirely parallelized, and can utilize multi-core CPUs to the fullest. Faster CPUs will be able to compute more frequent and timely movement plans for the airplanes, resulting in smarter flight routes.

The CPU tests run at a fixed resolution of 1280×1024, and most of the graphics options are drastically reduced. There are almost no post-processing effects, no complex shaders, no shadows, and none of the world outside what you see on screen is modeled. The idea is to limit the impact of the GPU so much that even budget, entry-level cards can display the tests so easily that they’re entirely CPU-limited.

The i5 blew past this test with flying colors better than a 3.0GHz Core 2 Extreme 9650 quad-core CPU would perform (score: 1678).

CPU Test 2 Score: 15.52 Steps /s

Physics: The Physics Test features a heavy workload of future generation game physics computations. The scene is set at an air race, but with an unfortunately dangerous configuration of gates. Planes trailing smoke collide with various cloth and soft-body obstacles, each other, and the ground. The smoke spreads, and reacts to the planes passing through it.

The test spawns one pair of gates for each CPU core. So, four gates in a quad-core CPU. If there’s a hardware physics card in the system, subtract one from that number and then add four (seven gates in a quad-core system). Each pair of gates is its own independent physically simulated “world” and does not interact with the other pairs of gates.

Since we didn’t have a PhysX card, the system performed at normal levels expected for the configuration.

Our Evaluation

Gaming

The tests of Core i5 indicate that its gaming performance will match or is better than that of the Core i7 920. This, more than anything, is likely due to the Lynnfields’  improving on the Turbo Boost feature. However, if you already own a high-end Core 2 Duo or Quad, upgrading only on the basis of gaming performance isn’t the best idea. If you are in the market for a new one, definitely buy the Core i5.

Power

We couldn’t test this feature ourselves, so we’ll take Intel’s word for it. Intel has been going to great lengths to ensure their processors use as little power as possible. Core i5 is no exception. The new power management feature throttles down the cores automatically when they aren’t being used. This, along with a general refinement of the manufacturing process has resulted in a processor that just sips at power. It is our guess that a Core i5 system, even when paired with a high-end graphics card, will idle at under 100 watts – for the entire system. This is an impressive achievement.

Overall:
The Core i5 750 looks to be a solid winner. Its true strength lies in the Turbo Boost Technology. With it, the processor can automatically overclock all four of its cores independently to match the workload at hand. Down-clocking works equally as well thanks to new power saving features. The only thing it is lacking compared to the other Lynnfield processors is hyper-threading.

This system is highly recommended for those looking to dip their toes into the Nehalem platform without breaking the bank. The Core 2 Duo and Core 2 Quad parts will eventually die out, putting an end to the LGA775 platform, so it only makes sense now to buy  this far superior system than invest a new in an old one.

Cheat Sheet:

If you’re as confused as a whole lot of us with all this information over-load, here’s a cheat sheet for use to compare different Intel’s offerings. (source: PC World)
Intel Lynnfield Chips

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