SIMPLE X58 OVERCLOCKING FOR DUMMIES
BSOD = Blue screen of death
BCLK = Bus clock / Cpu Host Frequency
VCORE = CPU Voltage / CPU Core Voltage
RAM = Random Access Memory
VDIMM = Memory Voltage / Dimm Voltage / Ram Voltage
QPI = Quick-path Interconnect
PLL = Phase-Locked Loop
CPU = Central Processing Unit
IMC= Internal Memory Controller (the IMC is on the CPU)
VTT = Voltage Tracking Termination
CPU VTT = IMC Voltage
HT = Hyper Threading (originally known as Multi Threading) intel renamed it
The main hint in overclocking is to work with the cpu first, and tweak the ram later. If you run your RAM a good amount below specifications, it should be stable as long as it is not
too far below spec, then you will have to lower the vdimm below factory specifications (i.e., 1.65 dropped down to 1.62 to compensate) because
too much vdimm can cause instability. Even if you set the vdimm to the manufacturer's specifications (usually 1.65v) it can still be too much.
if you are running 1866mhz ram at 1600mhz you will want to lower the VDIMM to around 1.62 or possibly even lower. Unfortunately, due to the limit of DRAM ratio's i.e., 2:6, 2:8, 2:10, 2:12 etc. It only leaves you so many options for memory speed. You will notice that overclocking the CPU in small increments also overclocks the ram equally. So, keep an eye on the
Actual DDR3 speed so you don't go over factory speeds. You can calculate the cpu speed by multiplying the base clock with the multiplier. 133 base clock/bus speed and a multiplier value of 21 = 2793 (intel rounds that up to 2.8ghz in the spec sheet) For calculating ram you take the base clock and multiplier it by the 2nd number in the DRAM ratio. So, 133 base clock at 2:10 dram ratio, we use the 10 to multiply... 133x10= 1333mhz ram speed.
If you crash with your memory below spec, its most likely because the CPU voltages are unstable. Once you can pass 50+ Linx tests and 11 hours of prime95 blend, then you can speed up the RAM knowing that any crashes you may encounter are because of incorrect
RAM related voltages (VTT and Vdimm). VTT will need to be increased along with the
CPU Uncore Frequency (usually +50mv for every 200mhz increase on Uncore) When going from stock (Core i7 920 @ 2.66ghz) all the way up beyond 4ghz, all you really need to change is
CPU Vcore,
CPU VTT and
QPI PLL Vcore and manually set
Vdimm to manufacturer's specification.
Everything else can be left on Auto. A lot of us like to lower the
CPU PLL Vcore and
IOH PLL Vcore because
1.8/Auto is just too high in most cases (Lower is always better).
Set the
QPI Frequency Selection to
4.8gt/s, that is the native speed for the the Core i7 920. As you overclock that speed goes up regardless to what it says in the bios. I've had no problems leaving that on auto.
Manually set your memory voltage and timings to the manufacturer's specifications. Make sure the difference between the CPU VTT and Vdimm is NOT greater than 0.5 volts. So if your VTT is +0mv (this comes out as 1.100v on a Non-Classified board) DO NOT set your vdimm to anything higher than 1.60v. Use a .45 difference just to be on the safe side. VTT @ +0mv = 1.200v on Classified boards, and 1.100v on Non-Classified Boards.
Each mv represents .001v So starting from 1.200 add 75mv you get 1.275, add 100mv and you get 1.300.
So lets say your Vdimm is 1.70 in bios. Subtract (0.45) from the vdimm and that will give you your lowest safe VTT.
Math Formula: (1.7) - (0.45) = 1.250
1.250 comes out to +50mv on a Classified board and +150mv on a Non-Classified Board. Keep the difference within this range to be on the safe side.
Once you get the memory set, and out of the way. You should find out what your default vcore is. Mine is 1.29375, When I set my vcore on auto, 1.29375 shows up in the bios as my actual cpu vcore. If you have a high default vcore, like 1.3 or above, this means you probably have a voltage hungry chip, and wont be getting an extreme overclock. Now that you know your default vcore, Leave Vcore on AUTO and set (With Vdroop) OR.... set your vcore 3 to 4 notches lower than the auto setting and set (without vdroop). Either way your vcore should be about the same during a 100% linx Load when using E-Leet to monitor.
Vdroop Control Explained
(Without vdroop)= during 100% load the vcore will jump up .023 to .032 volts. So if it's set to 1.25 in bios. You should see 1.273v to 1.282v during 100% cpu usage.
(With vdroop)= during 100% load the vcore will drop .03 to .05 volts. So if its set to 1.29375 in bios. You should see 1.24 to 1.26 during load. This also is a safety feature designed by intel so the cpu doesn't receive dangerous voltage spikes during load.
Note: The vdroop/vgain can be more drastic if you are not using a Classified board.
I leave vdroop off because i dont like seeing such a high vcore when idling, when its off, what you set in bios is right about what you get during idle. Vdroop is used for safety reasons, mainly to keep the Vcore from spiking during heavy cpu tasks.
Here I will try to explain what each MAIN voltage setting is for.
CPU Vcore is the main voltage for the CPU Speed in Mhz/Ghz
CPU VTT controls the Uncore Frequency. CPU VTT is the main voltage for the IMC, which is on the CPU.
QPI PLL keeps the on-chip memory controller in sync with the bclk. Whatever that means lol
VDIMM is the main voltage for the RAM.
IOH Vcore sets voltage for the north bridge which connects to the PCIE2.0, GPU, Memory, and CPU.
IOH/ICH I/O I think this is a voltage for the USB ports and possibly firewall and ethernet.
ICH Vcore sets voltage for the South Bridge which connects all motherboard features, cards (not PCIE2.0), and drives, to the CPU/memory on the North Bridge.
Manually set these settings into your bios
Set your CPU VTT to 1.3v, this should be good for a 3400mhz Uncore Frequency (a 2:10 DRAM ratio at around 3.6ghz cpu speed will give you 3400mhz on the Uncore frequency). If your auto setting for CPU Vcore is 1.3125v or above you should shoot for a lower first overclock, like 3.2ghz or 3.4ghz. If you do decide to go for a lower overclock start off with CPU VTT @ 1.2 and go up from there.
The CPU VTT Voltage can stay the same regardless of how high you overclock, as long as your Uncore Frequency stays the same as well.
Either use Turbo Mode or lower the multiplier down to any ODD number ie.. x19. Using the x20 multiplier requires more vcore at the same cpu speed. So if you must drop the multiplier use x19 or x21 for best results.
Turn HT OFF for your first overclock. This will help keep your temps nice and low. This will also give you more accurate BSOD's. Take a look at my BSOD section below, the Unknown Hardware Error BSOD will occur more often when HT is ON. That error usually points straight to the VTT voltage, but in this case, more Vcore was needed.
Note: Having HT on requires about .03 - .04 more on the CPU VCore when compared to HT OFF. It is also about 8-10 degrees hotter on the CPU during load.
Make sure CPU UNCORE Frequency is 2x the DRAM Ratio. So if you are using a 2:8 ratio, make sure UNCORE is at 16x. (2x8=16)
OVERCLOCK!
When you increase the bclck/cpu host frequency, you will see what your cpu speed is going to be. Shoot for somewhere between 3.2 and 3.4ghz if this is your first overclock, and this CPU can definitely do it. If you have an i7 920 D0, shoot for 3.4 - 3.6 for your first try.
Now that you've selected your cpu speed, double check everything. Here is what you should see...
Intel Speed Step = Disabled
Turbo mode = Enabled
HT = Disabled
Execute Disable bit = Disabled
CPU Spread Spectrum = Disabled
Actual CPU speed = 3220mhz - 3640mhz (depending on what you put)
bclck/cpu host freq. = 153 - 173 (same as above)
I used 153 - 173, as this is where you should start. Try 173 bclck if you are feeling bold, it should be fine.
Ram divider = 2:8
(make sure ram speed is not over its rated speed, preferably slightly underclocked)
Since my ram speed is 2000mhz I can use 2:10. Even 2:12 on low overclocks, but its usually a crap shoot because the 2:12 overclocks my uncore frequency way too high, and I you dont want to run higher than 1.45v on VTT for 24/7 usage.
RAM Timings = (whatever your specific ram is rated to run at) ie. 8-8-8-24
Set trfc to 88, you can lower this once stable if you wish
CPU Uncore Frequency = x16
Vcore = Auto (without vdroop)
CPU VTT = +100mv
Vdimm = 1.65v ( this is my ram's stock voltage, as specified by the manufacturer. DO NOT copy me, your ram might be 1.5v, make sure you check!)
Leave everything else on AUTO.
"These settings are good for 3220mhz - 3730mhz on my system. Once I fine tune the 3220mhz overclock, I find I can lower the Vcore to 1.100v and CPU VTT to +0mv." So after getting it stable, tweaking the voltages down as low as possible is your next priority!
Once you get all that situated in your bios, hit save and exit, and boot into windows. Find yourself Linx 0.6.4 or newer if there is one (i'm currently using 0.6.4). Double click the LinX application, (ie. LinX.exe) and look at the "Physical Memory Available" Bar. You want to make sure the "Memory(MiB)" is set to use "ALL" memory. You can select it by clicking ALL. So, if the Physical Memory Available is 4838MB (like mine is right now) when you click "ALL" it should be set to somewhere very close like 4834MB. Forget about the problem size as this is directly related to the amount of physical memory available for usage.
NOTE: The more memory you use, the longer the tests will take to complete.
Dont forget to set the amount of tests to run, or the amount of time to run. Its on the top right of linX. I like to do 3-4 tests while watching temps and GFLOPS. If the GFLOPS continue to decrease in descending order, it could mean your vcore is already too low. 1 notch up on vcore should be enough to fix it so the GFLOPS stay consistent. You can usually tell after 3 or 4 tests.
Example of too low Vcore....
TEST 1 GFLOPS 39.8758
TEST 2 GFLOPS 39.6852
TEST 3 GFLOPS 39.4286 ---------- I usually stop it right here if i see this. When I see test 3 doesn't jump up
TEST 4 GFLOPS 39.3198 above test 1 or 2 this means vcore is too low and most likely unstable.
Note: Make sure you have ALL programs closed (with the exception of monitoring software) and don't browse the web while testing, this can cause drops in your GFLOP numbers. Sometimes the gflop's will look fine after 3 or 4 test, but you will still get an error during LinX as a result of too low vcore. Increasing the Vcore a little will most likely allow you to pass that error. Linx errors after 10 tests is usually VTT related but could still be Vcore. Linx errors before 5-10 tests is almost always Vcore.
Once you have your vcore in a good spot, run 50 - 75 Tests with ALL memory to be sure your Vcore and VTT voltage's are stable. You can quit here and risk having a crash someday, or run prime95 blend for at least 12 hours. Once you pass all those tests, then you can start lowering voltages. For example, I like to get ALL my voltages to there lowest stable setting. CPU PLL and IOH PLL are 2 voltages that can be lowered below AUTO setting. Vdimm can be lowered below spec setting if your ram is underclocked. I recommend prime95 blend for any testing longer than 10 hours. It is not as hot, and more reliable to crash you if something is wrong in your memory configuration. LinX is more reliable to crash you if there is something wrong in your CPU Vcore or VTT configuration. Prime95Blend for 12+ hours is the best way to determine overall system stability.
What are Safe Voltages for my board?
Well to start off... Intel says to not go over 1.55 Vcore or 1.35 VTT. I personally think they are crazy but this is what is in their spec sheet. Read about it here Vdimm should stay at 1.65 or below. If you must over volt your ram make sure it is within the VTT range.
Any voltage that is below 1.200 at stock should not be raised above 1.45 (to be on the safe side)
This includes QPI PLL, ICH Vcore, IOH Vcore, and CPU VTT
Here I explain a few BSOD's
Clock interrupt was not recieved on secondary processor Almost 90% of the time it means Vcore is too low. Could also be incorrect Vdimm and QPI PLL in some cases.
Uncorrectable Hardware error 90% of the time this means VTT is too low. Having HT On will usually give you this BSOD instead of the CPU Clock interrupt BSOD. 
These 3 crashes below can be the most difficult to figure out.
IRQL_NOT_LESS_THAN_OR_EQUALThis usually happens when multiple settings are off ie. Uncore Frequency too high, Vcore too low, Memory speed/timings too fast, VTT too low. This can also happen when your memory is unstable.
System locks up and stays locked up (picture on screen is frozen) This usually happens when your memory is unstable or if your uncore frequency and VTT are off. This can also happen when you try to surpass your max bclk (the max your cpu can do).
System just restarts without any warnings This is a sign that multiple settings are most likely way off. There is'nt one particular setting that causes this. It could be a number of things all at once ie. vcore too low, VTT not in the sweet spot (not too high and not too low) memory speed/timings too high, uncore freq too high, vdimm.... etc.
If you cant seem to fix it, lower your overclock 100mhz, preferably go back to where you were stable. If it means going back 200mhz then that's fine. This time do a smaller jump in mhz, +100mhz instead of +200mhz (ex. 3.8ghz to 3.9ghz instead of 3.8ghz to 4.0ghz). See how much vcore you need, you are still going higher than your last stable overclock. You might find that this time going from (example 3.8 to 3.9) requires the same bump in vcore as 3.6 to 3.8 did. This will help you have an idea on how much vcore and VTT to set for the next 100mhz (3.9 to 4ghz)
(you can set windows to not automatically restart after a BSOD) This way if your PC crashes while you were gone, when you come back the BSOD will still be on the screen. To do this right click the My Computer icon and click properties. Then click advanced system settings and look for startup and recovery and click the settings button. In here you should see System Failure and under it a few check box's. Uncheck Automatically Restart and click ok.
Ok I'm stable at 3.6 - 3.9ghz now what? I want MORE!!!
If you want more, you are going to have to give more voltage. Same rule's apply though, keep memory under clocked. Don't just jump right for 4ghz+ unless you know your cooling can handle it. Not everyone can do 4ghz+ with safe temps.
So if you're stable at these 3.6ghz settings...
(These are just example settings)
3.640ghz
bclck = 173
Vcore = Auto/1.29375 (with vdroop)
VTT = +100
QPI PLL = Auto
Now you can bump up the voltages and go for a higher overclock. Moving up in increments of 100 - 200 mhz will give you a better idea on how much to increase the voltages. So for 3.640 to 3.850, I am going to add 0.05v on the Vcore, +50mv on the VTT, and 0.025 on the QPI PLL Vcore. Keep the same ram divider you used before, if you have to lower the ram divider then you will also be able to lower the VTT. Keep an eye on what VTT you need at certain Uncore Frequencies. ie. I use +100VTT for 3466mhz Uncore.
3.85ghz should look something like this with your first try, assuming the above settings are your lowest stable settings.
3.85ghz
bclck = 183
vcore= 1.34 (with vdroop)
VTT = +150
QPI PLL = 1.125 (probably could stay at auto)
4ghz+ Overclocking
Now for 4ghz and up. This is where it starts to get extreme. This should only be done if you are positive your cooling can handle it. CPU PWM, VTT PWM and CPU Impedance, QPI Comensation come into play when you get this high. You can start turning these up a little to help with your overclock. If your temps are too high on the Vreg just leave CPU PWM and VTT PWM alone as this should not stop you from reaching your goal.
QPI Compensation set to Less can help a high overclock but may cause further instability.
CPU Impedance set to less also helps a high overclock but not always. These settings are different for everyone.
The Main steps for overclocking 4ghz +
Step 1: Make an educated guess as to where you should set the VCore, VTT, and QPI PLL. Refer to your lower overclocks for an estimation.
Step 2: Run LinX with ALL memory.
Step 3: If Gflops are good (not descending) continue testing until you pass 50 tests or until you crash. If you get a linx error or crash and your Gflops are looking good, it could still need more vcore so give it a bump.
Step 4: If you crash refer to my BSOD section, hopefully you were there to see the BSOD.
Step 5: Depending on what crash you've received you need to adjust 1 to 2 settings at a time, then test again. Raise or lower each setting at a time by 1 or 2 notch increments and then test. If that doesn't help change it back and adjust something else. The goal is to get farther and farther into testing. Keep repeating this until you are able to go further. The more tests you can pass, the closer you are to getting 100% stable.
Step 6: Don't forget to tweak CPU PLL, IOH PLL(Classified only), QPI PLL. These are very important for 4ghz+ overclocks. Always start low.
Here is a nice low overclock that doesn't bottleneck my video cards and gives me optimum gaming performance with minimum voltage.
3.42ghz HT/Turbo ON @ 1.164v during load (1.15625 in bios (without vdroop)).
CPU HOST FREQUENCY = 163
DRAM RATIO 2:10
Uncore Frequency = 3253mhz (x20)
RAM = 2000mhz 8-8-8-24 underclocked to 1633mhz 6-6-6-15
QPI PLL VCORE = 1.1 (AUTO)
IOH PLL VCORE = 1.275 (auto = 1.8)
CPU PLL VCORE = 1.275 (auto = 1.8)
VDIMM = 1.63 (spec = 1.65)
CPU VTT = +25mv (1.225)
IOH Vcore = AUTO (1.1)
IOH/ICH I/O = AUTO (1.5)
ICH VCore = AUTO (1.05)
Max temps after 3 hours 100% LinX load.....
Hottest CPU Core 1 = 58c with a Thermalright Ultra 120 Extreme and 2x3000rpm fans push/pull
North Bridge = 48c (no fan)
Vreg = 45c
System = 35c
Here are a bunch of my full Bios Templates, along with others submitted from fellow evga members.
http://forums.evga.com/tm.aspx?m=179016
I'm stable at my goal overclock, but my ram is still low, how can I speed it up?
You can either lower the timings to your ram, or up the divider.. ie 2:8 to 2:10. I recommend using the 2:8 divider with lower timings as this is easier and keeps the uncore frequency low. Lets say your ram is rated 1600mhz but is only running at somewhere between 1400 and 1500. That is as much as 100 to 200 mhz below stock. So with that you should be able to lower your timings from 8-8-8-24 to 7-7-7-20 ( or 7-7-7-20 to 6-6-6-18) while keeping the vdimm at 1.65v. If it crashes try upping the vdimm. Raising the vdimm is a necessity when overclocking ram. Lowering the Vdimm can also help in the overall overclock stability when your ram is underclocked. So if your ram is 200 - 300 mhz underclocked you should be able to lower the vdimm from 1.65 to 1.63. Remember too much vdimm can be unstable! If you use the 2:10 divider and it overclocks your ram beyond 1600mhz, you will have to either raise the vdimm or loosen the ram timings (possibly even both). This should all be done after you've completed a full round of testing. ie. 50-75 tests of linx and 11+ hours of prime95blend. Then just use prime95 blend to test your overclocked ram, knowing that you already passed 11 hours with it underclocked, now if it crashes you will know you have to tweak the ram related motherboard settings ie. Vdimm, VTT and Timings.
Here is some good info on vdimm voltages. Here is a quote from the article...
http://www.anandtech.com/memory/showdoc.aspx?i=3426 Personally, with the right board, cooling, and
BIOS settings, 1.7V~1.8V should be fine
"BIOS settings" as in... the difference between the CPU VTT and Vdimm is NOT greater than 0.5 volts.
WARNING
DO NOT use E-Leet for changing the NB voltages, ie. IOH/ICH, IOH VCORE, ICH VCORE. It can cause extreme instability and you may have to re-install windows to fix it. It's something weird that corrupts the display driver if you change them while running any type of graphics. May not happen the first time but if done too many times it can happen. It comes out of nowhere and hardlocks your system during gaming even though you are stable. I only use E-Leet to tweak
Vcore or
VTT after a LinX error. Or to see if my current voltages that I've set in the bios can overclock any higher.
It is best to do all your main overclocking settings in the bios. Then test. If you get a simple linx error then you can increase a voltage in E-Leet.
A few good Questions and Answers I read a thread on here about VDROOP... it seems like it might be better for the CPU to keep it on... will this greatly impede my OC'ing? No, it doesnt Impede your overclock at all. I like it because it keeps the vcore low when idle and only bumps it up during load. Others like it on. I prefer it off. I believe you can acheive cooler temps with it being off.
Also, HTing... it seems that you can get a better OC with it off. What provides better performance?
It's not that your overclock is any better because it's off, it's just that you will be able to set your vcore .04 volts lower, and your temps will be around 8 degrees lower as well. In the battle of 3.6ghz w/ HT on vs 4ghz w/ HT off. The 3.6ghz is actually hotter but also provides the best performance because I am using windows 7. Most people would say to turn HT OFF in XP and Vista because the OS doesn't support it, some say it still helps a little, its your call here.
Another question... right now I'm at 3.6 with 173x21 ... but this only gives me about 1300mhz on my RAM! If I were to increase it from 2:8 to 2:10 it would blow me over to 1700mhz... so what do I do?
Dont blow over to 1700mhz thats for sure. The only way to get your ram higher now is to either increase the overclock on the cpu or lower the timings. But all this comes after you test out stable. You dont want to start messing with the timings when you aren't sure if the vcore and vtt is stable. Once you are stable then you can come back and set the ram timings lower. For example your at 173bclck 1300mhz 8-8-8-24, set the ram to 7-7-7-18 and test to see if that is still stable.
...example 1300mhz 7-7-7-18 is probably equal to 1550mhz 8-8-8-24
When you need more voltage (like when the GLFOPS are going down) how do you know whether its better to raise the VCORE or the VTT?
That Gflop trick is strictly for the Vcore. VTT is different. Only LinX errors after 10 tests and the BSOD (Unknown Hardware error) will tell you that your VTT is off. If your GFLOPS are not descending as if your vcore is too low, and you do get a linX error, it is most likely the VTT that is too high or too low. Only trial and error will tell.
How much additional temp is 4000mhz going to cause? With a 76-77 max after a few LINX tests with 3.6ghz... how can I accomplish it?
I can tell you 4ghz is going to go over 85c. If you truly need 1.27 for 3.6ghz with HT on, then you will most likely need around 1.37vcore for 4ghz with HT ON. If you really want 4ghz you need better cooling or you need to turn HT OFF. I suggest you get yourself a nice stable 3.6ghz overclock and keep it that way. That's what I did. Yea, I can do 4ghz with 80c max temps and HT on but who cares, If I can get the same performance at 3.6ghz and keep my temps below 65c during linX, what do you think is better?
If i raise my qpi pll with this enable me to lower my vcore? or am i just dreaming? (read this on another site)
I have found that once you have all the voltages "just right", you should be able to magically lower the vcore a little more. I used to think i needed 1.3625 for 4ghz, because anything lower than 1.36 would give me the 'cpu clock interrupt' BSOD (which usually means vcore is too low)
After hours of testing and after tweaking all my other voltages down or up, (while leaving the vcore at 1.36) I then gave a small bump in cpu pwm and then tried lowering the vcore once again. This time I was able to pass 50 tests with 1.3375 vcore.
Here is what I did.
My QPI PLL was a little higher than it should have been (but still rock solid stable with 1.36vcore). So I was able to lower that from 1.3 to 1.25.
Also my vdimm was too low. I used to run my ram at 1610mhz 6-6-6-18 @ 1.60 vdimm, and it would pass LinX for 50+ tests and I could game 24/7 without ever crashing... but Prime95blend would error on one of the threads. So I raised the vdimm to 1.63 and blend passed a full round of tests (about 11 hours)
CPU PLL was stable at 1.65v for 4ghz and 1.575 was not. IOH PLL can go down to 1.35 or even lower. Both of these default to 1.8 and I have not noticed a difference in temps when lowering them alone.
My VTT was also a little high. I was using +50mv and was able to lower it to +25mv.
Then I raised the CPU PWM 1 notch.
post edited by OV3RCLK4 - 2014/07/03 14:39:15