Basic Concepts of Overclocking Intel Core i3/i5/i7 CPUs

First off you need to identify your hardware. Learn everything you can about your system and then search for it in Google. Luckily, there will be others using the same hardware rig, hence googling it’s always a nice trick to check upon your system’s limits. That’s the reason why hardware forums will never die.

Micro-architecture

The CPU micro-architecture has taken a huge leap from the 65nm Core to the new generation 45 and 32nm (SandyBridge) and 22nm (Ivy Bridge) technology, it has brought many changes not only to the CPU’s but also to the chipset and motherboard design and functioning. This is what makes overclocking the i3/i5/i7 CPU’s so much different to their predecessor LGA 775 CPU’s — meaning Core2Duo/Quad (65nm).

The naming convention can be a bit confusing so let us look at the various CPU and their names:

[toggle title=”Codenames, die size and sockets”]

  • Nehalem – 45 nm die size | 1366 socket
  • Bloomfield – 45nm die size | 1366 socket
  • Lynnfield – 45nm die size | 1156 socket
  • Westmere/Clarkdale: 32nm die size | 1156 socket
  • Westmere/Gulftown: 32nm die size | 1366 socket
  • SandyBridge: 32nm die size | 1155
  • E-SandyBridge: 32nm dize size | 1155/2011
  • IvyBridge: 22nm die size | 1155/2011

[/toggle]

First we have the Nehalem family which are all 45 nm CPU’s that included i7 1366 Bloomfield (i7-920 i7-975) and Lynnfield socket 1156 i5/i7 (i7-750 to i7-860). These are all quad cores with HT except for the i5 which has no HT. Then the next family is Westmere which is essentially die shrink 32 nm CPU version of Nehalem and again you have the Clarkdale (socket 1156) in flavors of i5 and i3, both dual core processors with HT. Gulftown which is the hex-core CPU’s and not available yet are also part of the Westmere family and features 6 physical cores with HT and will be socket 1366 only. Last year we had the SandyBridgefamily which are all 32nm CPUs included all i-X families.

With Sandy Bridge, Intel has tied the speed of every bus (USB, SATA, PCI, PCI-E, CPU cores, Uncore, memory etc.) to a single internal clock generator issuing the basic 100 MHz Base Clock(BClk).With CPUs being multiplier locked, the only way to overclock is to increase the BClk, which can only be raised up to 5-7% without other hardware components failing. As a work around, Intel made available K/X-series processors which feature unlocked multipliers; multiplier cap of 57 for Sandy Bridge. For example during IDF 2010, Intel demonstrated an unknown Sandy Bridge CPU running stably overclocked at 4.9 GHz on air cooling

After 6 months, E-SandyBridge have launched and there is alternative method known as the BClk ratio overclock. Nowadays we are happy to see the new 22nm Ivy Bridge family.

So, to summarize, we have socket LGA 1366, LGA1156, LGA1155 and LGA2011 which are essentially the board platforms that carry certain 45 and 32 nm and 22nm CPU variants. Both platforms are DDR3 where the 1156 and 1155 are dual channel only.

Intel Core i3, i5, and i7 CPU’s

The following are the different CPU’s available today on the market, except for the Gulftown hex cores which will be available late 3rd quarter of 2009.

[tabs tab1=”i3 530, 540″ tab2=”i3 2120, 2100″ tab3=”i3 3220, 3225, 3240″]

[tab]Core i3 (Clarkdale – i3 530, 540) – First Generation

The least expensive and least powerful choice are the Core i3 chips. These are currently limited to two physical cores with both the i3 530/540 models supporting Intel® Hyper-Threading Technology. At this time, all i3 CPUs have two pieces of silicon (or dies) in the CPU. One contains the actual processing cores and all of the L1, L2, and L3 caches. The second die contains a GPU (graphic processing unit) which is capable of outputting video without the use of a dedicated video card when used with an H55 or H57 based motherboard. This second die also contains the PCIe controller and the dual channel IMC (Integrated Memory Controller). The first die is manufactured on a 32nm process, the second die is manufactured on a 45nm process. The two die are linked with the Intel QPI (Quick Path Interface). All Clarkdale i3 CPUs work only on LGA1156 based motherboards — quite obsolete and hard to find these days.

[/tab]
[tab]Core i3 (SandyBridge-i3 2120, 2100) – Second Generation

The entry level of SandyBridge CPUs — 32nm — are identical to low end systems with embedded GPU (using HD3000/2500). They have 2 cores with HyperThreading, based on motherboards with LGA 1155 socket. Also there is dual channel IMC built inside the CPU and it has 3MB L3 cache.
[/tab]

[tab]Core i3 (Ivy Bridge -i3 3220, 3225, 3240) – Third Generation

The entry level of Ivy Bridge CPUs — 22nm — are identical to low end systems with embedded GPU (using HD4000/2500). They have 2 cores with HyperThreading, based on motherboards with LGA 1155 socket.

[/tab]

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[tabs tab1=”i5 650, 660, 661, 670″ tab2=”i5 750″ tab3=”i5 2500K” tab4=”i5 3450, 3330, 3470, 3570, 3550″]

[tab]Core i5 (Clarkdale – i5 650, 660, 661, 670)First Gen

Dual core i5 CPUs (Clarkdale) are identical to the i3 CPUs, but also include Intel® Turbo Boost Technology. All Clarkdale i5 CPUs work only in LGA1156 based motherboards.[/tab]

[tab]Core i5 (Lynnfield – 750) – First Gen

The most powerful Core i5 of First Gen; Quad core i5 CPUs (Lynnfield) are identical to the low end i7 CPUs, the only exceptions being their lack of Intel® Hyper-Threading Technology, Intel® Virtualization Technology for Directed I/O (Intel® VT-d) and Intel® Trusted Execution Technology (Intel® TXT). All Lynnfield i5 CPUs work only in LGA1156 based motherboards.

[/tab]
[tab]Core i5 (Sandy Bridge – i5 2500K) – Second Gen

The high end Sandy Bridge processor that rocks with 4 core CPU’s made for LGA 1155 based motherboard. These CPU are manufactured on the 32nm process. They have dual channel IMC’s built into the CPU die. The PCIe controller is not part of the CPU, but is build into the chipset (on the motherboard), the CPU and chipset are linked with a Ring Technology, outperforming the QPI. There is no HyperThreading.

[/tab]

[tab]Core i5 (Ivy Bridge -i5 3450, 3330, 3470, 3570, 3550) – Third Gen

The mid range Core i5 (Ivy Bridge) are quad core CPUs made for LGA 1155 base motherboards. These CPUs are manufactured on the 22nm process. They have dual channel IMCs built into the CPU die. The PCIe controller supported 3.0 x16 lanes boosting the GPU performance even more that previous generation. They come with 6MB L3 cache while running at frequency range of 3.0 to 3.4 GHz. There is no HyperThreading.[/tab]

[/tabs]

[tabs tab1=” i7 860, 870″ tab2=”i7 920, 940, 960, 965/975″ tab3=”i7 980x” tab4=”i7 2600K, 2700K” tab5=” i7 3930K” tab5=”i7 3770K” tab6=”i7 3960X”]

[tab]Core i7 (Lynnfield – i7 860, 870) – obsolete

The low end Core i7 (Lynnfield) are quad core CPUs made for LGA1156 based motherboards. These CPUs are manufactured on the 45nm process. They have dual channel IMCs and PCIe controllers built into the CPU die. All i7 CPUs include Intel® Hyper-Threading Technology and Intel® Turbo Boost Technology. Lynnfield based CPUs are unique in that they do not have a QPI. Because the PCIe and memory controllers are both integrated on the CPU die, there is no need for the QPI. They are known to have incredible IMCs and are capable of sustaining extreme memory bandwidth.

[/tab]
[tab]Core i7 (Bloomfield – i7 920, 940, 960, 965/975) – obsolete but still rocks

The mid range Core i7 (Nehalem) are quad core CPUs made for LGA1366 based motherboards. These CPUs are manufactured on the 45nm process. They have triple-channel IMCs built into the CPU die. The PCIe controller is not part of the CPU, but is built into the chipset (on the motherboard), the CPU and chipset are linked with a QPI. All i7 CPUs include Intel® Hyper-Threading Technology and Intel® Turbo Boost Technology.

[/tab]
[tab]Core i7 (Gulftown – i7 980x)

The high end Core i7 (Gulftown) are hex (six) core CPUs made for LGA1366 based motherboards. These CPUs are manufactured on the 32nm process. They have triple channel IMCs built into the CPU die. The PCIe controller is not part of the CPU, but is built into the chipset (on the motherboard), the CPU and chipset are linked with a QPI. All i7 CPUs include Intel® Hyper-Threading Technology and Intel® Turbo Boost Technology. Please understand that these new 32nm CPUs are more sensitive to high voltages, and have been known to fail even when core temperatures are well within “safe” limits.

[/tab]

[tab]Core i7 (Sandy Bridge – i7 2600K, 2700K)

The best edition of 2500K including HyperThreading — so 4 cores and 8 threads. Please note the the “K” means unlocked for overclocking. So if you have 2600 instead of 2600K, sorry but you cannot overclock. Note the “K” in the end of the part, meaning this CPU is unlocked ready to be overclocked. If you have the same CPU but without the “K”, sorry you cannot overclock.[/tab]

[tab]Core i7 (E-SandyBridge – i7 3930K)

The high end E-Sandy Bridge are 4/6 core with HT, made for LGA 2011 based motherboards (preferably using the X79 platform). The processor runs at 3.2GHz (max turbo 3.8GHz) while is fully equipped with 12MB L3 Cache. Note the “K” in the end of the part, meaning this CPU is unlocked ready to be overclocked. If you have the same CPU but without the “K”, sorry you cannot overclock.[/tab]

[tab]Core i7 (Ivy Bridge -i7 3770K)

The high end of Ivy Bridge platform is released in September 2012 made for LGA 1155 based motherboards. These CPUs are manufactured on the 22nm process. They have dual channel IMC’s build into the CPU die. The PCIe controller is version 3.0×16 lanes boosting your GPU performance even more. The CPU runs at 3.5GHz and has 8mb L3 cache. Note the “K” in the end of the part, meaning this CPU is unlocked ready to be overclocked. If you have the same CPU but without the “K”, sorry you cannot overclock.[/tab]

[tab]Core i7 (E-SandyBridge -i7 3960X)

The beast of Intel that rocks with 6 cores and 12 threads running each core at 3.3GHz while 3.9GHz when Turbo is enabled. The model is supported by 2011 socket LGA motherboards. Finally, it uses 15MB L3 cache. The “X” means eXtreme edition.[/tab]

[/tabs]

The smaller the die size, the less power it needs. Thus 22nm CPUs are less power-hungry than 65nm CPUs. Bare in mind that modern processors bring inside them an embedded GPU, which makes things even harder to overclock. The IMC is not that good as it used to be, so many overclockers tend to have their RAM frequency at lower levels.

 

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