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[Project completed] Core i5-750 @ 3.4GHz

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Jan 28, 2010
Core i5-750 system - moderate overclocking at 3.4GHz - cool and low power PC

[FINISHED - Last update @ 2010.08.22]

This guide is for the ones who like to bring i5-750 closer to it's "true potential" without any risk for their components on the long therm. I am writing this based only on my personal experience with my components. After a lot of searching trial and testing, I managed to SAFELY overclock my system to 3.4GHz, keeping very low voltages and temperatures. This is a system designed to run on hot ambient up to 40ºC.

Keep in mind that settings I found suitable for my system won't work the same on others. If you are planning to overclock your own using my settings as reference, it would be wise to increase voltages a little, replacing for example the CPU VCore at 1.21 and Vtt at 1.20 or 1.25, plus set your RAM "Performance Enhance" on STANDARD to see if you can boot like that with your system at 3.4 GHz and get no errors. If it works, then set "Performance Enhance" on TURBO, test again, then again, if all is well, lower voltages bit by bit till you find the sweet spot where your system never crash.

Why 3.4GHz? Because:
 3.4GHz over 2.66GHz default is a decent overclock of roughly 30% (27.82%) and it is more then enough for all my needs. I will see no benefits to run a 4GHz rocket, my games would not run much more faster and my work won't be done essentially quicker, except for the one where I use CPU at 100% for extended periods of time, and even for that I am happy with 3.4 GHz.
 I want to be completely on the safe side, I don't like fried CPU's.
 Keeping low voltages means less heat and less stress on components that leads to longer life; I intend to keep my computer a very long time.
 Power consumption is a LOT lower with all power saving features enabled. At 4 GHz you need to disable them.

Possibile frequency increase for i5-750 in percentage:
i5-750 ------------------- CPU freq. --- % increase over default value
Default frequency ------ 2667 MHz --- 0%
Moderate overclock ---- 3400 MHz --- 27.82 %
High overclock ---------- 3800 MHz --- 42.90 %
Extreme overclock ----- 4000 MHz --- 50.40 %

o MB Gigabyte P55-UD3 (BIOS version: F9)
o CPU Intel Core i5-750
o CPU Cooler Scythe NINJA MINI rev B (SCMNJ-1100)
o Therm paste Arctic Silver Ceramique (2.5 g)
o RAM Kingston DDR3 4 GB 1600 MHz KHX1600C8D3K2/4GX (CL8)
o SVGA Sapphire Radeon HD 4670
o HDD Western Digital WD1001FALS (RAID 0 member 1)
o HDD Western Digital WD1001FALS (RAID 0 member 2)
o HDD Western Digital WD1001FALS (RAID 0 member 3)
o HDD Western Digital WD20EARS (external storage)
o DVD-R - none
o DVD-RW Sony AD-5240S-0B
o Sound card onboard
o Speakers QuickShot QS-835
o LAN onboard
o LAN Adaper SiS900 PCI
o Bracket to connect any SATA HDD at eSATA + external SATA input
o CASE Lian li PC-K7B
o PSU Fortron Blue Storm II 500
o Keyboard Benq i150 (keyboard from kitt Key+Mouse)
o Mouse A4Tech SWW-48 (PS2)
o UPS APC Back-UPS CS, 650VA/400W (+Bandrige Power Cable)
o Monitor Horizon 2206SW - 22" LCD
o Scanner Hewlett-Packard ScanJet 2400
o OS Microsoft Windows 7 Home Premium 64 bit English OEM



- BIOS: J36_170x20
It took me a lot to understand that I have to enter MANUALLY all default values on BIOS, because on Gigabyte motherboards [AUTO] means really weird things (for example Vtt voltage left on AUTO was set by BIOS to almost 1.4v !!! when the default value is 1.100v and maximum specified by Intel is 1.21v). I am not sure about the other manufacturers but I would recommend to all Gigabyte users to write the default values manually on BIOS to protect their components on the long therm.
UPDATE: Looks like starting with BIOS update F8C these issues were corrected by Gigabyte. However, I still prefer to set my options manually rather then trusting AUTO.

o BIOS update using QFLASH and 1Gb USB stick. I noticed USB stick of 4Gb (FAT32 same as stick of 1gb) can't be detected by QFlash as a valid drive.

o BIOS settings:
Saving BIOS profiles

o System Memory Multiplier set at 8. This allow rising BCLK to 170 while keeping the memory frequency at only 1360 MHz at 7-7-7-20 timings. This allow me to set Performance Enhance on TURBO without causing instability. This apparently have an effect on Round Trip Latency (RTL) parameter and in my case the difference was clearly measurable in all windows applications. I pondered a lot between setting RAM at 1600 MHz with 8-8-8-20 and Performance Enhance on STANDARD as many users on different forums recommend, and the above settings. I underline again: RAM at 1360 MHz at 7-7-7-20 timings with Performance Enhance on TURBO -> windows "feel" much faster and everything is moving smoothly compared with setting RAM at 1600 MHz with 8-8-8-20 and Performance Enhance on STANDARD.
More about RTL here: http://www.anandtech.com/show/2869/6

o TurboBoost deactivated from BIOS since bumping the multiplier to x24 at a frequency of 170x24=4080 MHz, is a sure crash at these low voltages, I don’t even want to test that. All power saving features are explicitly ENABLED.
However if you are willing to increase Vcore to make it stable, TurboBoost is possible but I do not recommended it.

After almost a month to ensure myself of system stability, I set my CPU Vcore and VTT voltages at the lowest 100% percent stable values: CPU Vcore = 1.09375, Vtt = 1.170.

Nothing appears here because all HDD's and DVD-RW are handled by the RAID.

- CPU-Z (CPU on idle and full load with Prime95)
o Idle

o Full load

o Caches

o Mainboard

o Memory

o SPD Slot 1

o SPD Slot 3

o Graphics

o About

I posted the latest config at CPU-Z validator http://valid.canardpc.com/show_oc.php?id=1219013

- POWER CONSUMPTION (including monitor and entire system connected to the UPS)

o idle (170x9=1530MHz) = 116W (CPU=idle, GPU=idle)

o full load (170x20=3400MHz) = 180W (CPU=full load, GPU=idle)

o full load CPU+GPU(170x20=3400MHz) = 232W (CPU=full load, GPU=full load) (Prime95+Furmark in same time)

- CPU TEMPERATURES (recorded after 23 minutes of INTEL BURNTEST - ambient temp = 22ºC)
o idle (170x9=1530MHz) = 31ºC (the highest core)
o full load (170x20=3400MHz) = 60ºC (60,58,58,58 for each core after 23 min. of IntelBurnTest at Maximum stress level)
o Note1: INTEL BURNTEST is the most stressful test for PC and in real programs you can’t get temps this high even if you are using CPU at full load for hours.
o Note2: With this computer at 3.8GHz the speed (Gigaflops) on IntelBurnTest was 53? GFlops but the CPU temperature hit over 85ºC and power consumption increased to 310W. This is not for me, thank you very much. Take a look at this screenshot I made at that time:

o Note3: These temperatures were recorded with Core Temp 0.99.5.
IMPORTANT! Different programs read temperatures from different sensors for example HW Monitor program and Gigabyte's Easy Tune 6 (included on mobo DVD) read sensors from motherboard and report them as CPU temperature which is totally incorrect, while Core Temp and Real Temp read the internal CPU sensors and show the true CPU temperature.

- STORAGE. I do a lot of filming on-site and video editing, so a big and fast storage system was a must. The (relatively) cheap 2TB drive, I keep as an external drive for backups because I didn't want to go for RAID1. Access time and transfer speed for the RAID 0 matrix:

- NOISE. The four 12 cm vents (two intake on front of the case and two exhaust - one on back of the case and one on power supply) do a wonderful job in keeping the system very well cooled and surprisingly quiet. CPU cooler is very silent as well; the loudest components are by far the 3 HDD's and the video card when I play 3D games. Overall the system is fairly quiet for my taste, and under the desk where i keep it is totally not disturbing.

- TEST1 = Memtest86+ v4.10 (MS DOS) => 3 hours memory testing on MS-DOS mode, 5 time coverage => 0 errors, PASSED

- TEST2 = MEMTEST (Windows)
4 instance running 234% coverage => 0 errors, PASSED

- TEST3 = PRIME 95 running for 3 hours => 0 errors PASSED

Standard 1024Mb, 3 times => 0 errors PASSED
Maximum 3461Mb, 10 times => 0 errors PASSED (1392 sec.)

- TEST5 = 3DMark 2006 (tests: select all, settings: 1680x1050, noAA, run each test 10 times, all the rest at default) => 0 errors PASSED
3DMark score 7425, SM2.0 = 2574, HDR/SM3.0 = 2973, CPU = 4964

- TEST6 = FURMARK v.1.8.2
o Benchmarking: fullscreen, 1680x1050, noAA, 600000ms (10 min.) => 0 errors PASSED
Average fps = 21 (min=18, max=33)

GPU temp = 77ºC (normal) -> 78ºC (max.) (22ºC ambient)
o Stability test: windowed, 1024x768: 600 sec => 0 errors PASSED
Average fps = 32
GPU temp = 71ºC (normal) -> 73ºC (max.) (22ºC ambient)

- TEST7 = PRIME95 + FURMARK Stability test (running both on same time)
FURMARK Stability test: windowed, 1024x768: 600 sec => 0 errors PASSED
o Average fps = 32
o GPU temp = 76ºC (max.) (25ºC ambient)

A long time stability test is needed for LGA 1156 platforms, as were seen computers fully stable that pass all stress tests flawlessly and then crash at random. This seems to happen because of a too low VTT - V Core voltages on overclocking. Since I tried to keep voltages (and temperatures) to a minimum for my modest overclock, this test is perhaps the most important indication that the computer is FULLY STABLE.
Playing CIV4, NWN2, Flatout2UC and UO for several hours on different days => no crash, all stable, 0 errors, PASSED

- TEST9 = Apex DC++ and uTorrent
Downloading/Uploading with high speed => no crash, all stable, 0 errors, PASSED

Converting 104 video files (4 converter instances to use CPU 100%), 687minutes.; average 396sec per file (6.60min) =>0 errors, PASSED

The only problem I encountered with my setup is a short beep on the motherboard speaker at random amounts of time (maybe once at one-two hours), which can be caused maybe by memory settings (i couldn't find the cause for sure). I noticed that if I set my memory at 1600MHz (my RAM is rated at 1600) or if I enable XMP profile from BIOS (which do the same thing), the beep appears at larger intervals. The thing is, I couldn't find any problem with my memory at 1360MHz, all tests OK, my computer is never unstable, so, I choose to just ignore that random beep.

I am planning to keep this computer with these settings a very long time from now on, and I am very happy to have found the perfect overclock for me after all the tests and tries.
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