XXChronicXX

                                         

 

 

                                             This Guide is best for people with the Core i7 920 D0/C0  

   

 

        Overclocking the i7 is very easy, it just takes patience. First thing is to make sure the ram speed is set lower than the actual speed of the ram. For example if you have ram that is rated to run @ 1600mhz  8-8-8-24, you should be running somewhere around 1500-1600mhz 8-8-8-24 when testing your overclock. Unfortunately due to the limit of DRAM ratio's, (ie. 2:6, 2:8, 2:10, 2:12 etc) it only leaves you so many options for memory speed. You will notice, overclocking the CPU also overclocks the ram. So, keep an eye on the actual ddr3 speed so you don't go over. 

                                                            Here are some abbreviations

                                                     BCLK = Bus clock / Cpu Host Frequency
                                                  VDIMM = Memory Voltage / Dimm Voltage
                                                           QPI = Quick-path Interconnect
                                                                PLL = Phase-Locked Loop
                                                            CPU = Central Processing Unit

                                                          VTT = Voltage Tracking Termination
                                                                   HT = Hyper Threading

   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 spec, it should be stable as long as its not too far below spec, then you would have to lower the vdimm to compensate, because too much vdimm can be unstable, even if you set the vdimm to the manufacturer's specifications. If you crash with your memory below spec, the CPU  voltages are unstable. Once you you get it to pass 100+ Linx tests and 10 hours of prime95 blend, then you can up the RAM speed, knowing that you will only have to tweak the RAM related voltages ie. (VTT and Vdimm).  VTT will need to be increased if you are increasing the CPU Uncore Frequency

                                                  
   When going from stock (Core i7 920 @ 2.8ghz) all the way up beyond 4ghz, all you really need to change is the CPU Vcore, CPU VTT and QPI PLL Vcore and manually set Vdimm to manufacturer spec. Everything else can be left on auto. If you want to be safe you can set the QPI Frequency Selection to 4.8gt/s,  that is the native speed for the Core i7 920. As you overclock that speed goes up regardless to what it says in the bios. Ive 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 1.2v on my Classified) DO NOT set your vdimm to anything higher than 1.65v

Use 0.45 volts just to be on the safer side.

VTT @ +0mv = 1.200v on Classified boards and  1.100v on the E758 Board

 

Each mv represents .001   So starting from 1.200 add 99mv you get 1.299, add 100mv and you get 1.300.

If your vdimm is 1.73 in bios. Subtract (0.5) from the vdimm (1.73) and that will give you your lowest VTT.

Math Formula:  (1.73) - (0.5) = 1.230

1.230 comes out to +30mv on my classified board and +130mv on the E758. This means DO NOT set VTT below that number, this will exceed the 0.5 difference and damage your cpu. I recommend staying a good distance away from the 0.5 difference.

   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 have a voltage hungry chip, and probably wont be getting a very high 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.

Here I will try to explain what each MAIN voltage setting is for.

CPU Vcore is the main voltage for the CPU Speed

CPU VTT voltage controls the Uncore Frequency and bclk

QPI PLL keeps the on-chip memory controller in sync with the bclk.
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 CPU/memory on IOH

                                                         Here I explain vdroop control

(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 a linX load.
(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 it makes overclocking easier because if the vcore is too high, its not going to hurt me for stability.

 

                                                         Manually set these settings into your bios

   Set your CPU VTT to +100mv, this should be good for a 3400mhz Uncore Frequency (usually 2:10 divider at around 3.6ghz will give you 3400mhz on the Uncore). 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 +0mv and go up from there.

CPU VTT is related to the Uncore and bclck/cpu host frequency. The higher you take these, the more CPU VTT you will need.

Make sure Turbo is ON this allows for the lowest possible vcore for your overclock, turning it off drops the multiplier down to 20 thus requiring you to raise the bclck higher, which can require more vcore. Odd Multipliers like 21 and 19 seem to be better than the even multipliers. So if you must drop the multiplier I would use x19.

Set HT to ON if you are using windows 7.
Set HT to OFF if you are using XP or Vista as they do not support Hyper Threading.

Note: Having HT on requires about .03 - .04 more on the CPU Voltage as compared to HT off. It is also about 8 degrees hotter on the CPU during load. Maybe more. 

 

Make sure CPU UNCORE Frequency is 2 times the DRAM Ratio. So if you are using a 2:8 ratio, make sure UNCORE is at 16x.   (2x8=16) 

                                                    OVERCLOCK!  
   Now, when you increase the bclck/cpu host frequency, you will see what your overclock is going to be. Shoot for somewhere between 3.2 and 3.4ghz if this is your first overclock and this chip can definitely do it. If you have an "i7 920 D0" shoot for 3.4 - 3.6

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 = Enabled
Execute Disable bit = Disabled
CPU Spread Spectrum = Disabled

Actual CPU speed = 3220mhz - 3640mhz
bclck/cpu host freq. = 153 - 173

I put 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, use 2:6 even)
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 too high.

RAM Timings =  (whatever your specific ram is rated to run at) ie. 8-8-8-24
Set trfc to 79 or even 88 to start and then lower once you pass the tests.
CPU Uncore Frequency  = x16

Vcore = Auto (with 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."

   Once you get all that situated in your bios, hit save and exit, and load up 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 usually means your vcore is too low and you are not stable. 1 notch up on vcore should be enough to fix it so the GFLOPS dont descend.  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.
TEST 5 GFLOPS  39.2753
TEST 6 GFLOPS  39.1531
TEST 7 GFLOPS  39.0315
TEST 8 GFLOPS  38.9748
TEST 9 GFLOPS  39.8498

Note: This Gflop trick is not consistent and does not always work this way.
Sometimes the gflop's will look fine after 3 or 4 test, but you will still have 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 several hours of testing is usually VTT related but can still be Vcore. Linx errors before 5-10 tests is almost always a too low 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 is stable. You can quit here and risk having a crash someday, or run Linx for 100+ tests and prime95 blend 11 hours. Doesn't have to be back to back. You can run Linx one night while u sleep, and prime95blend the next night. 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. 

                                       Here I explain a few BSOD's
Clock interrupt recieved on secondary processor Almost 90% of the time it means Vcore is too low. Could also be vdimm(I had this error and fixed it by adjusting vdimm)
Unknown Hardware error  Usually means VTT is too low or too high.

                                              These 3 crashes below can be the most difficult to figure out.
IRQL_NOT_LESS_THAN_OR_EQUAL This usually happens when multiple settings are off  ie. Uncore Frequency too high, Vcore too low, Memory speed/timings too high, VTT too low/high. 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. Try lowering it or raising vdimm to fix.
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 underclocked. 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. Not saying that you couldn't just shoot for a higher overclock right off the bat. By all means, do so if you have the cooling. 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

Note: this all depends on how voltage hungry your chip is. Some can do a 1.15 vcore @ 3.6 and a 1.2 vcore @ 3.85.... Refer to your auto vcore.... anything above 1.2875 is voltage hungry.

                                                                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 QPI Comensation come into play when you get this high. You can start turning these up a little to help with your overclock. They do not always help though.
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. (your cpu decides that)

QPI Compensation set to Less will help a high overclock.
CPU Impedance set to less also helps a high overclock but not always.

                                               

                                                    The Main steps for overclocking
Step 1: Make an educated guess as to where you should set the vcore, vtt, and qpi pll, referring to your lower overclocks for an estimation.
Step 2: Run LinX for 3 to 4 runs, make sure the Gflops are good. If you can run 3-4 runs without crashing. Lower vcore 1 notch and see if gflops are still ok. If they are ok, lower vcore again 1 notch. Do this until you see your gflops decreasing or until you crash. Then bump it back up 2 notches and it should be enough. Test to make sure. Once stable try to lower one notch and test again.
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 good, it could still be vcore, as the gflops trick is not consistent.
Step 4: If you crash, hopefully you were there to see the BSOD. If your system  Locks Up or just freezes, this usually points to the memory and/or Uncore frequency.
Step 5: Depending on what crash you've received you need to adjust 1 setting at a time, then test again. Raise VTT up one or two notches. If that doesn't help lower it back down and raise something else. Keep repeating this until you are able to go further in your testing. The more tests you can pass, the closer you are to getting 100% stable. 

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                = 1.60     (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
North Bridge = 48c (no fan)
Vreg = 45c
System = 35c 

Here are a bunch more of my full Bios Templates
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? 

    Now 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. Thats 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 to 1.66 or 1.67. Upping the vdimm is a necessity when overclocking ram. If your ram is 200 - 300 mhz underclocked you should be able to lower the vdimm below spec. Too much vdimm can also be unstable! If you use the 2:10 divider and it overclocks your ram beyond 1600mhz, you will have to tweak the vdimm and loosen the ram timings. This should all be done after you've completed a full round of testing. ie. 100 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. You CAN change them, just not with any open windows on the screen. 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 hardlock crashes your system during gaming even though you are stable.

I only use E-Leet to increase vcore after a LinX error. Or to see if my current voltages that I've set in the bios can overclock any higher. 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?

2slick4u

I'm having problems getting my ram timing to boot..
my ram is rated at 8-8-8-24 but i cant get that timing to boot.. anyone help :(