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Overclocking: Get The Performance Of A Core i5 From Core i3
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1. Cranking Up Core i3 To 4.4 GHz

Intel’s 32 nm processor generation undoubtedly has a lot of potential. The quad-core models usually reach 4+ GHz, and the dual-cores can go much further. Therefore, we decided to test the cheapest Core i3 offering, the Core i3-530, and see what this entry-level desktop processor has in stock for you.

What’s In a Name?

This is actually a good question. Although Intel's product portfolio appears to be straightforward—the Core i3, Core i5, and Core i7 families appear to be laid out logically enough—Intel created a number of caveats you'll need to be able to navigate.

The Core i3 models, for example, are dual-core chips, and they don’t come with all of the features found on more expensive CPUs. This is entry-level hardware to be sure, and there are only two SKUs available, the Core i3-530 at 2.93 GHz and the Core i3-540 at 3.06 GHz.

The Core i5 is available either with two cores (600-series) or four cores (700-series). All Core i5 processors support Turbo Boost functionality, but only the dual-core versions accelerate AES encryption and decryption, and come equipped with Hyper-Threading. Be careful with the mobile Core i5 lineup—not all of these chips support AES-NI. The quad-core Core i5-750 is a 45 nm part, while all dual-core models are manufactured at 32 nm. And beware the Core i5-750S, since this low-power version is less efficient than the regular product.

And then there's Core i7. The 800-series drops into the processor interface as all of the aforementioned CPUs, namely LGA 1156. These support Hyper-Threading, but not AES acceleration. The flagship model i7-980X features six cores and is manufactured at 32 nm, while the rest of the 900-series features four cores and a 45 nm process. All 900-series CPUs employ the LGA 1366 interface.

Back to Basics

Let’s get back to some important facts: Intel processors are almost universally more expensive than AMD’s, but most offer significant overclocking headroom. In fact, many processors, including the Core i5 dual-cores and the i5-750 quad-core, deliver better performance per watt at reasonable overclocked frequencies than at their respective stock speed. Therefore, we decided to purchase the cheapest Core i3 available to see how fast it can go and find its most efficient clock speed.

2. Intel's Core i3-530 CPU

The Core i3-530 is Intel’s entry-level offering. Although there is a lower-end product, the 2.80 GHz Pentium G6950 with 3MB of shared L3 cache, we decided to buy the i3-530 because it offers faster integrated graphics, higher supported memory clock speeds, and Hyper-Threading technology.

The Core i3-530 has 4MB of cache and runs at 2.93 GHz. That may not sound like a big difference, but we found that overclocking to 4 GHz and higher is a fairly simple affair. A 1.345V peak voltage was all we needed to have it operate stably at 4.0 GHz. We also tried 1.40V at 4.5 GHz, but this setting turned out to be unreliable. We decided to let it go, as we didn’t want to fry the processor.

The most noticeable difference between the Core i3 and Core i5 dual-core models is the i3's absence of Turbo Boost technology and AES-NI. Turbo Boost accelerates the processor in various steps as long as the thermal envelope allows. AES-NI is an additional instruction set that speeds up encryption and decryption on supporting applications that utilize AES.

Trusted Execution Technology and VT-d for Directed I/O were also dropped on the Core i3 CPUs, but these features are somewhat insignificant for the end-user community. Everything else is identical between the two families: the 733 MHz HD Graphics engine, 16 PCI Express 2.0 lanes, dual-channel DDR3-1333 support, and the 73W TDP. The i3 series works on virtually any LGA 1156 motherboard available today. Let’s look at our overclocking results.

3. Gigabyte's P55A-UD7 Motherboard

We looked at this motherboard in March when we analyzed the performance impact of different PCI Express implementations, because bandwidth-intensive peripherals like USB 3.0 and SATA 6Gb/s controllers can be bottlenecked on many board designs.

The P55A-UD7 is Gigabyte’s LGA 1156 flagship, and it implements a PCI Express switch capable of distributing bandwidth dynamically across all available 16 PCI Express lanes even if you technically require more bandwidth.

We based our overclocking tests on this motherboard because of its luxurious component lineup that not only includes a long feature list, but also a strong and flexible voltage regulator circuit that can access up to 24 phases. Paired with Gigabyte’s philosophy of using a generous amount of copper (called Ultra Durable 3) and a solid heat pipe solution, this makes one of the best platforms for intense overclocking. We took the board from a 133 MHz base clock all the way past 200 MHz. In earlier overclocking tests, we learned that this board can actually go higher, so we know that the processor is acting as our frequency, not the motherboard.

I’ll quickly summarize this board's most impressive features. Three of the four x16 PCI Express slots can run graphics cards, and both AMD's CrossFireX and Nvidia’s 3-way SLI are supported (Ed.: bear in mind that you probably don't want to use more than two graphics cards; any more than one card requires dividing 16 lanes of PCI Express connectivity between devices). Gigabyte accommodates memory speeds up to DDR3-2600. Not least of all, this motherboard offers future-facing USB 3.0 and two SATA 6Gb/s ports.

4. Overclocking Settings: 2.93 GHz To 4.4 GHz

Our CPU-Z screenshots show some key overclocking milestones. The images list all of the voltage settings and clock speeds in idle and at load. Keep in mind that while Core i3 doesn't support Turbo Boost, it does support SpeedStep to lower clock speed and core voltage in order to reduce power consumption and heat dissipation. You'll find a comprehensive settings table on the following page.

133 MHz DMI, 2.93 GHz

164 MHz DMI, 3.6 GHz

182 MHz DMI, 4.0 GHz

200 MHz DMI, 4.4 GHz

5. Test Setup And Overclocking Table
System Hardware
HardwareDetails
Performance Benchmarks
Motherboard
(Socket LGA 1156)
Gigabyte P55A-UD7  (Rev. 1.0); Chipset: P55; BIOS: F4
CPU Intel
Intel Core i3-530 (32 nm, 2.93 GHz, 4 x 256KB L2 and 4MB L3 Cache, TDP 73W)
CPU Intel IIIntel Core i5-750 (45 nm, 2.66 GHz, 4 x 256KB L2 and 8MB L3 Cache, TDP 95W, Rev. B1)
CPU Intel IIIIntel Core i5-661 (32 nm, 3.33 GHz, 2 x 256KB L2 and 4MB L3 Cache, TDP 87W, Rev. B1)
RAM DDR3 2 x 2GB DDR3-1333 (OCZ3G2000LV4GK 8-8-8-24)
GraphicsSapphire Radeon HD 5850
GPU: Cypress (725 MHz), Graphics RAM: 1,024MB GDDR5 (2,000 MHz), Stream Processors: 1,440
Hard DriveWestern Digital VelociRaptor, 300GB (WD3000HLFS), 10,000 RPM, SATA 3Gb/s, 16MB Cache
Power SupplyEnermax Pro 82+, EPR425AWT
System Software & Drivers
Operating SystemWindows 7 Ultimate x64
Updated on 2010-03-03
Drivers and Settings
Intel Chipset DriversChipset Installation Utility Ver. 9.1.1.1025
Intel Storage DriversMatrix Storage Drivers Ver. 8.​9.​0.​1023
Audio Benchmarks and Settings
BenchmarkDetails
iTunesVersion: 9.0.3.15
Audio CD ("Terminator II" SE), 53 min.
Convert to AAC audio format
Lame MP3Version 3.98.3
Audio CD "Terminator II SE", 53 min.
convert WAV to MP3 audio format
Command: -b 160 --nores (160 Kbps)
Video Benchmarks and Settings
BenchmarkDetails
Handbrake CLIVersion: 0.94
Video: Big Buck Bunny (720x480, 23.972 frames) 5 Minutes
Audio: Dolby Digital, 48000 Hz, 6-Channel, English
to
Video: AVC1 Audio1: AC3 Audio2: AAC (High Profile)
Mainconcept Reference v2Version: 2.0.0.1555
MPEG-2 to H.264
MainConcept H.264/AVC Codec
28 sec. HDTV 1920x1080 (MPEG-2)
Audio:
MPEG-2 (44.1 kHz, 2-Channel, 16-Bit, 224 Kbps)
Codec: H.264 Pro
Mode: PAL 50i (25 FPS)
Profile: H.264 BD HDMV
Application Benchmarks and Settings
BenchmarkDetails
7-ZipVersion 9.1 beta
LZMA2
Syntax "a -t7z -r -m0=LZMA2 -mx=5"
Benchmark: 2010-THG-Workload
WinRARVersion 3.92
RAR
Syntax "winrar a -r -m3"
Benchmark: 2010-THG-Workload
WinZip 14Version 14.0 Pro (8652)
WinZIP Commandline Version 3
ZIPX
Syntax "-a -ez -p -r"
Benchmark: 2010-THG-Workload
Autodesk 3ds Max 2010Version: 10 x64
Rendering Space Flyby Mentalray (SPECapc_3dsmax9)
Frame: 248
Resolution: 1440 x 1080
Cinebench 11.5Version 11.5 Build CB25720DEMO
CPU Test single and multi threaded
Adobe Photoshop CS 4 (64-Bit)Version: 11
Filtering a 16MB TIF (15000x7266)
Filters:
Radial Blur (Amount: 10; Method: zoom; Quality: good)
Shape Blur (Radius: 46 px; custom shape: Trademark sysmbol)
Median (Radius: 1px)
Polar Coordinates (Rectangular to Polar)
Adobe Acrobat 9 ProfessionalVersion: 9.0.0 (Extended)
== Printing Preferenced Menu ==
Default Settings: Standard
== Adobe PDF Security - Edit Menu ==
Encrypt all documents (128-bit RC4)
Open Password: 123
Permissions Password: 321
Microsoft PowerPoint 2007Version: 2007 SP2
PPT to PDF
PowerPoint Document (115 Pages)
Adobe PDF-Printer
FritzFritz Chess Benchmark Version 4.3.2
Synthetic Benchmarks and Settings
BenchmarkDetails
3DMark VantageVersion: 1.02 Patch 1901
Options: Performance
Graphics Test 1
Graphics Test 2
CPU Test 1
CPU Test 2
PCMark VantageVersion: 1.0.2.0 Patch 1901
PCMark Benchmark
Memories Benchmark
SiSoftware Sandra 2010Version: 2010.1.16.10
Processor Arithmetic, Cryptography, Memory Bandwith


Overclocking Table

Core i3-5302,933 MHz3,300 MHz3,608 MHz3,806 MHz4,004 MHz4,202 MHz4,400 MHz
Multiplier22x22x22x22x22x22x22x
Base Frequency133 MHz150 MHz164 MHz173 MHz182 MHz191 MHz200 MHz
RAM10x
8x8x8x6x6x6x
RAM1,333 MHz1,200 MHz1,312 MHz1,384 MHz1,092 MHz1,146 MHz1,200 MHz
System Idle Power80W80W80W82W82W83W84W
System Peak Power127W129W135W138W145W155W170W
BIOS Vcore0 mV0 mV0 mV25 mV50 mV100 mV175 mV
VTT
1.1V1.1V1.1V1.12V1.14V1.16V1.2V
CPU-Z VT idle0.944V0.944V0.944V0.976V1.008V1.056V1.120V
CPU-Z VT load1.168V1.168V1.184V1.200V1.232V1.280V1.344V
PCH
1.8V1.8V1.8V1.8V1.8V1.8V1.8V
RAM
1.5V1.5V1.5V1.5V1.5V1.5V1.5V
Fritz chess benchmark5363
59856529
69077201
75517916
Stable
Yes
YesYesYesYesYesYes
QPI44
36
32
32
32
28
28


6. Benchmark Results: Synthetics

We decided to compare the Core i3-530's results with a Core i5-661 dual-core (one of the fastest i5 models) and a Core i5-750. The latter is Intel’s entry-level quad-core model, and one of the SKUs we most commonly recommend to power users on a budget.

It's impressive to see how much faster AES data encryption can be when the processor supports AES-NI. Even our 4.4 GHz overclock didn’t make too much of a difference compared of the impact of hardware-based encryption acceleration.

The overall encryption score favors the AES-NI-enabled Core i5 dual-core. But the Core i5-750 quad-core also delivers sufficient computing power to be faster than the highly overclocked Core i3-530.

Memory bandwidth most significantly depends on DDR3 memory speeds. These vary depending on the selected DMI speed and memory multiplier selection. We intentionally did not overclock the memory at this time, as this involves much higher costs for premium, high-speed DDR3 DIMMs.

7. Benchmark Results: PCMark And 3DMark Vantage

Clearly, the high overclocks show their effects. Keep in mind that graphics performance is also included, which explains the Core i5-661's relative strength.

8. Benchmark Results: Applications And Archiving

The 4.4 GHz Core i3 dual-core is fast enough to compete with the Core i5-750 quad-core. Once again, the Core i5-661 delivers greater performance than the Core i3-530 at the same nominal clock speed. This stems from the Turbo Boost feature not supported on Core i3 CPUs.

Cinebench on one thread scales nicely with every megahertz of clock speed.

Once Cinebench is switched to multiple threads, the Core i5-750 comes out on top. The other results scale with their clock speed.

Photoshop users clearly need a multi-core processor. The image editor benefits more from additional execution cores than from increased clock speeds.

The chess software Fritz scales best with additional processing cores, but the clock speed increases lead to linear performance gains, as well.

7-Zip is very computing-intensive if you run LZMA2 and medium or higher compression.

9. Benchmark Results: Power Consumption

First of all, it is great to see that system idle power doesn’t change very much. Even the fastest 4.4 GHz setting only caused a small increase from 80W to 84W. This is more than acceptable.

Peak power consumption increases with clock speed, and the increase is larger at the fastest settings because of the necessary voltage tweaks. However, the fastest 4.4 GHz setting at 1.345V actually requires the same system peak power as if a Core i5-750 at 2.66 GHz and stock voltage were used. We found this interesting mainly because 4.4 GHz dual-core chip and 2.66 GHz quad-core processor deliver roughly the same performance at roughly the same power consumption.

10. Benchmark Results: Single- And Multi-Threaded Efficiency

Single-Threaded Efficiency

Runtime measurements and the total power used to complete this workload are intriguing. The 4.4 GHz overclock produced the shortest processing time and almost the same total power draw.

Multi-Threaded Efficiency

A look at the multi-threaded applications used in our efficiency run shows that the Core i5-750 quad-core CPU is faster than our highly overclocked Core i3. However, the latter still beats the Core i5-661 by a considerable margin.

11. Benchmark Results: Overall Efficiency

Now we’ll look at the full efficiency workload, which includes most of the benchmarks presented above.

The total runtime is shortest on the two fastest overclocks. Core i5-750 gets beaten here.

The total power used is lowest at 4.0 and 4.2 GHz on the Core i3-530. Interestingly, the stock speed for this processor also produced the highest total power requirement.

Runtime related to total power used yields our efficiency score. The winner is the Core i3-530 at 4.2 GHz, which delivers the best performance per watt, and hence represents the most reasonable overclock. The 3.8 and 4.0 GHz clocks are similar, but both 3.6 and 4.4 GHz reduce power efficiency. Our Core i3-530 processor actually gains a lot of efficiency with the first overclocking setting (2.93 to 3.33 GHz).

12. Best Overclock And Conclusion

We purchased a retail Core i3-530 processor and used it on all of the overclocking tests detailed earlier. Slight voltage tweaks were unavoidable to ensure system stability at 3.8 GHz and up. The combination of Gigabyte’s P55A-UD7 and the Core i3-530 was amazingly stable at all times, except when we tried to cross the 4.5 GHz line. This was just too fast for this particular processor. A 4.2 or 4.4 GHz clock delivers vast performance improvements that set the Core i3-530 at performance levels beyond the Core i5-600-series and into performance levels typically reached by quad-core products.

As you can see in the diagram above, the Core i3-530 overclocked to 4.2 GHz delivers the highest power efficiency, expressed in performance per watt-hour. The score is a synthetic number resulting from the division of our performance results with the power consumption readings. Unfortunately, the 2.93 GHz stock speed delivers the worst power efficiency, so it makes a lot of sense to overclock the CPU at least a bit. This won’t jeopardize reliability or impact idle power, but it provides more horsepower to work on intensive workloads. This is the key to delivering great efficiency.

Going beyond 4.2 GHz requires significant voltage tweaks that negatively impact efficiency. You should only do this if you really know that the remaining speed upgrade delivers real benefits. In any case, a Core i5-750 quad-core might be the better investment for power users if budget allows. It results in similar system idle power and peak power at the same level as a Core i3 overclocked to 4.4 GHz. Then again, it’s important to mention that such a quad-core chip could still be overclocked on its own, yielding even more speed.