- Mar 27, 2005
- 1,005 (0.22/day)
- South Africa
|Processor||Intel i7-920 @ 4.0GHz LGA1366|
|Motherboard||Intel DX58 Smackover Motherboard|
|Cooling||TRUE 120 with 2x120mm Thermalright FDB-1600 and 8x120mm Zalman/Coolermaster Case Fans|
|Memory||16GB DDR3-1333 Corsair @ 8-8-8-19|
|Video Card(s)||Gigabyte GTX 1070 FE|
|Storage||Intel 520 240GB + Intel X25-M 80GB + 4TB Seagate/WD Storage|
|Display(s)||24" Samsung SA350 + 24" BenQ G2410HD + 2x 22" Samsung 2253GW's + Hyundai 19" B91D+|
|Power Supply||Corsair TX750W PSU|
zAAm's Core i7 Overclocking Basics Tutorial
I've been looking at i7 overclocking for a while now and have yet to see a proper, well thought out thread explaining everything there is to know about the subject. Although I don't presume this thread will fill that gap, I'll try my best to help out new users to get the most (or at least a reasonable amount ) out of their i7's with this basic instruction manual. I presume you already have a basic knowledge of overclocking. If not, please read this first. Right, let's get started!
Ok, so I've got the chip, what's next?
First things first, check that you have the right hardware! The right motherboard and memory will make a difference in your overclocking efforts. Choosing a decent brand motherboard (I would recommend an Asus or Gigabyte, but there are equally good ones out there and I don't believe I'm *entirely* impartial) will ensure that you can raise the base frequency more and with greater stability.
Regarding memory, try to get a higher rated speed so you have some overclocking headroom. I would recommend at least DDR3-1333 modules although DDR3-1600 would probably be best (I'll explain why a bit later). The use of higher rated memory modules is to give you more room to move between multipliers without overclocking the memory in the process and thus will give you a more flexible overclocking system. In the same breath though, since i7's have triple channel memory controllers, the use of anything higher than DDR3-1600 will likely result in only tiny performance increases. Timings aren't that important for our overclocking purposes so I'm not going to go too much into this subject, but tighter timings will definitely give better performance overall as lower latencies speed up the whole memory subsystem. Again, choosing a decent brand like Corsair, OCZ, G-Skill, Crucial or similar will give you more peace of mind and likely better stability overall, although as with most things, with higher priced RAM you get diminishing returns.
An important aspect of overclocking (if not THE most important) is cooling. You're stressing your components beyond their certified limits so they are bound to generate more heat than normal. Unfortunately, the i7 is no exception. Not by a long shot! Actually, it's one of the hottest chips out there, easily reaching 80 degrees celcius at stock frequencies when stress testing.
Now, before I move on the actual cooling bit, let's just talk about measuring the temperatures. The best way would be some sort of calibrated external temperature measurement device but since most of us don't live in an electronic shop, the internal temperature diodes on the i7 will do fine. If you've ever tried to read the i7's temperature with different programs, you'll have noticed that most of them give entirely different readings. This is because Intel decided that the i7 should report its temperature as the distance from the core's maximum temperature (Tjmax in this case, which means the maximum junction temperature). Uhm, now how does this work in practice? If it reports a temperature of 30 degrees, it still has a 30 degree buffer that it can heat up before reaching its maximum temperature. This unfortunately gives false readings to older monitoring programs that don't specifically support the i7. I've been experimenting with a few programs and I've found two of them that give accurate readings:
RealTemp 3.0 (TPU's own temperature monitor)
HWMonitor 1.14 (CPUID).
Choosing a cooler
First you'll notice I'm not going straight to overclocking since I DO NOT recommend overclocking an i7 with its stock cooler! I suggest you read that again to make sure you remember it. If you choose to use the stock cooler when overclocking, you have to be either crazy or stupid, since the temperatures can soar into the 90's or even 100's on load...
Again, I'll not go too much into this subject, as you'll find plenty of cooling threads on this forum, be it water or air cooling. I would recommend installing your cooling system and ensuring your load temperatures are below 60 degrees at least before attempting to overclock.
Diving straight into the BIOS
This is the place where the magic will happen. As you will find out, overclocking the i7 is a bit different than most CPU's, but once you get to know the settings it isn't difficult to understand all the underlying principles and how they influence your overclock. Although BIOS options differs between manufacturers (and even models), there should be options to set the following:
- BClk/Base Clock/Base frequency
- CPU Multiplier
- Uncore Multiplier
- Memory multiplier
- Intel Turbo Boost
- HT/Hyper Threading
- Intel SpeedStep/Power management
- CPU Voltage
- QPI/Vtt Voltage
- IOH/NB Voltage
- Memory Voltage
Setting the frequency
The first step to overclocking your i7 is setting the base frequency or base clock. On the i7 this will be 133MHz default. Ultimately, you'll be aiming for around 200MHz on this setting, but for now, just set it at a more reasonable 150MHz. I prefer doing my overclocking in smaller steps because it's easier to identify the components that are holding back the overclock. If you immediately set the base frequency to 200MHz and your system won't POST, there's a whole list of components that might be the culprit. But don't worry, we'll get there eventually
Setting the multipliers
Next, we are going to adjust the CPU, Uncore and Memory multipliers.
The CPU Multiplier is just what it says, it determines the CPU core frequency as 'n multiple of the base frequency. For the i7 920 for example, the default CPU multiplier is 20x, which gives 133MHz x 20 = 2660MHz, the stock 920 frequency. We want to keep this at the default setting of 20 (for the 920).
The Memory multiplier sets the speed at which the RAM operates. You'll need to make sure your memory can operate at the speed set by this multiplier. For now, set this at 6x (which equals a memory speed of 6 x 150MHz = 900MHz or DDR3-900) to make sure memory isn't holding you back from getting the maximum CPU overclock. If for some reason your memory modules won't boot at such a low frequency, try setting this at 8x until you've reached a high enough BClk frequency that the modules will boot.
The Uncore multiplier governs the speed at which all the components in the CPU other than the cores operate. Always ensure this multiplier is at least twice that of the memory multiplier. There are accounts that some motherboards won't boot when this multiplier is exactly twice that of the memory multiplier, so I recommend setting this at 2x+1 that of the memory multiplier. If you've set your memory multiplier at 6x, this should be set at 13 (2x6=12+1=13).
Disabling certain features
Since we want to focus on getting the correct CPU frequency, I suggest you disable features in the BIOS such as SpeedStep and Turbo Boost as well as any other power management features that will cause the BIOS to alter the CPU frequency or voltage.
Now, here comes the scary part . Your BIOS probably has a number of voltages you can set, but we will focus on setting the CPU and QPI Voltages at the moment. Since our memory is running lower than rated, we know they are getting enough voltage at this point.
Adjusting the CPU Voltage can be a tricky business and no two CPU's are alike. I would recommend setting the CPU Voltage from 1.25V (default) to around 1.35V for a C0 stepping or 1.30V for a D0 stepping. This will ensure the CPU has enough juice to stay stable at relatively high frequencies. This will differ greatly as you move between different Bclk frequencies and I would recommend you don't exceed 1.4V as most CPU's will not benefit from the added voltage and will produce significantly more heat. Notice that the voltage setting in the BIOS will be slightly higher than that actually recorded due to voltage droop (may be as much as 300mV!).
Next we will look at the QPI Voltage. This is another setting you will have to experiment with, but I recommend setting it at around 1.30V to start (just below the core voltage). You can always drop this voltage when conducting the stability tests later on.
The IOH voltage can be left at default for now (probably at around 1.1V). This setting might not need changing at all unless you increase bclk significantly and want to improve stability. Even then it probably won't have to be increased to anything above 1.25V.
A note on HyperThreading
It is largely accepted that turning HT off in the BIOS will allow for higher overclocks as the CPU will run slightly cooler. I for one prefer to leave HT on since I would need the additional threads more than faster individual threads because I am a huge multitasker. Again, this depends on what you use your computer for and it might be best for you to experiment with this setting on and off to see which delivers better results in your environment.
Now the time has come to, you guessed it, reboot (I might suggest praying at this point ). If your computer POSTS correctly with no errors, check in the BIOS if the temperature is still low enough and then boot into Windows (Or possibly Linux if you prefer). I would suggest you then check the temperatures again with one of the above mentioned programs to determine the approximate idle temperature. If your PC does NOT POST correctly, you'll need to double check that all the settings are correctly set and that your CPU voltage is high enough. I haven't heard of a single i7 user who couldn't POST with a Bclk of 150MHz so I believe you'll be safe here. However, if this should happen, you could try increasing the CPU voltage.
Now, if this temperature is decent (around 40 degrees celcius or lower), run a stress testing program (preferably OCCT or Prime95 or something that stresses ALL 8 threads! Or 4 if HT is turned off) while checking the temperatures for around 15min. If the temperature peaks at around 70 degrees you're still okay.
If the test succeeds, I suggest you repeat the whole process, increasing the Bclk by 10-20MHz each time, while ensuring the memory and uncore multipliers are set accordingly, until you find that you've reached your target frequency.
If the test fails, try increasing the CPU voltage a step to add some stability.
When you've reached your target (possibly 200MHz Bclk, 4GHz CPU), I would highly recommend running the stress testing programs again but for a much longer period this time to ensure your CPU will be stable at this frequency. I'd recommend running OCCT or Prime95 for at least an hour. If the test passes without errors and the temperatures are within limits, you have yourself a certified, overclocked, beast of a CPU!
If there is anything you wish to add to this guide or if you wish to point out an error, please feel free to notify me