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Intel Core i5-2500K Sandy Bridge CPU E-mail
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Written by Hank Tolman   
Monday, 03 January 2011
Table of Contents: Page Index
Intel Core i5-2500K Sandy Bridge CPU
Features and Specifications
Closer Look: Core i5-2500K
CPU Testing and Results
AIDA64 Benchmark Tests
Passmark PerformanceTest
PCMark Vantage Benchmark Tests
SiSoftware Sandra Tests
Cinebench R11.5 Benchmarks
Street Fighter IV Benchmark
x264Bench HD 3.0 Test
Sandy Bridge Final Thoughts
Intel Core i5-2500K Conclusion

Closer Look: Core i5-2500K

The launch of Sandy Bridge brings a whole new architecture to the table. This was also the case when Clarkdale/Arrandale launched and we moved to the LGA1156 socket. With those processors, the 32nm CPU and 45nm GPU were combined onto the same die. This was the first large-scale release of on-die graphics, though they had been talked about for a long time. In the Sandy Bridge architecture, the on-die GPU moves to a 32nm process as well and the IMC moves onto the die. The smaller process lets Intel use roughly the same amount of space for the new Sandy Bridge die, but it can fit a lot more transistors.


Another difference is that Sandy Bridge CPUs will come with one of two versions of the on-die graphics; either the 2000 or the 3000 version. Also, while Clarkdale/Arrandale processors took advantage of turbo boost, Sandy Bridge boasts turbo boost usage for the GPU independent of the CPU. This is good news for gamers who choose to use the on-die graphics. If their game, like most, requires heavy GPU loads, the turbo boost can leave the CPU at stock speeds and clock up the GPU to improve performance.

The Intel Core i5-2500K comes equipped with a 6MB shared L3 cache. Since the Nehalem architecture, where each core had a dedicated 2MB of cache, Intel has gone towards shared cache. In the Sandy Bridge architecture, the L3 cache is not only shared across all four cores of the Core i5-2500K, but also with the integrated GPU.


Another interesting cache feature of the Sandy Bridge CPUs is a tiny L0 instruction cache integrated with the L1 cache known as a Decoded Uop Cache. This caches instructions as they are decoded without discrimination. All decoded instructions run through this ~6KB cache. Old instructions are overwritten as new ones come along. This cache is designed to help alleviate front-end operation for commonly performed tasks.


Intel has also added a physical register file to their Sandy Bridge CPUs. AMD has talked about doing the same thing and it's a product of the growing size of Out-Of-Order execution hardware. It's grown quite a bit and with the inclusion of Advanced Vector Extensions (AVX) in the Sandy Bridge, the size of operands running through the OoO hardware would have become 256-bits. So Intel decided to put in a physical register file that will store the micro-op operands allowing the OoO to only carry pointers, rather than the data itself. Additionally, Sandy Bridge keeps the AES-NI introduced in Westmere and enhances Large Number Arithmetic Throughput. We should notice this in our CPU tests, especially the arithmetic processor tests and compression tests.


In order to speed up processing, Intel changed the way the parts of the die interconnect by creating what they call a ring bus. Older Intel architecture had each core with a separate path to the L3 cache. This isn't so bad if every core has its own cache, but when you have a shared cache between all the cores and the GPU, there isn't a lot of room to give everything its own path. The ring bus works basically how it sounds and each component of the die has its own location along the bus. Doing things this way gives the Sandy Bridge L3 cache great bandwidth and helps to reduce latency.


With everything on die now, we are moving away from older terminology like "Northbridge". The Sandy Bridge CPUs have a "System Agent" that controls the 16 PCI Express Lanes (they can be split into two x8 lanes), the DMI interface, the Memory Controller, and the Display Engine. The system agent also has a power control unit that controls all power management and reset functions, has separate voltage and frequency than the CPU cores, and offers power and thermal management for the PCI Express.


All these improvements and changes are great, but what are they worth? Let's get into testing the Core i5-2500K to see how its performance matches up to the price.



# GamerKyle 2011-01-06 20:39
I agree with the that every new line of processors comes with new motherboards. To me this is quite silly and I wish that they would not do as such. It is also a fault when Intel is placing quite the restriction on overclocking even with the K models.

Either way I am most likely going to get the i5 2500k since it is very strong. Also the price is rather cheap at $211 when currently the i5 750 is $200 and the i5 760 is about $209 dollars. Since I did not upgrade following the first i series I would need to get a new motherboard anyway.Integrated graphics means little to me since as a gamer I would get a higher end GPU regardless. I just have to make sure the motherboard is p67 not H67 for overclocking and such.

Anyway nice read, thanks for the article.
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# MrJMG 2011-02-23 14:57
If the p67 motherboards do not use the GPU on these new chips does that mean the GPU potential goes to waste I.e. If it were to make use of it, then in a standard system would you have, in effect, two graphics cards (with the intel HD GPU plus whatever other dedicated graphics card you use working together)?
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# RE: MrOlin Coles 2011-02-23 15:12
Only H67-Express motherboards can utilize Sandy Bridge integrated graphics, because only those motherboards have the DVI/D-SUB/HDMI output ports built-in. NVIDIA is already working with Intel on this very solution. Using Optimus technology, paired with Lucid Logic 'GPU Virtualization' software (yet unannounced), the Sandy Bridge CPU will be able to enable QuickSync + GPU.
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# mrzikkun 2012-03-24 11:35
nahh. actually h61 also have dvi, hdmi ports, dont know about d-sub(need it?). so actually use h61 and run this cpu is could be cheap, than buy a h67 or whatever that expensive twice
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