I7 960 overclock

So I bought and built my current rig about a year ago and man do I wish I had done a little more research.

My system is:

ASUS Rampage iii Formula Motherboard
Intel i7 960 @ 3.2 GHz
Corsair H70 watercooler
12GB of Corsair Dominator RAM

If I had known about the difference between OC'ing with a locked vs unlocked multiplier, I would've built my rig around a 2600k. Now I'm stuck between having to manually overclock which is confusing as hell to me, or shelling out $1000 for a 990x.

So I want to get my 960 running at a stable 4GHz. I started by setting a BCLK of 160, thinking the memory multiplier would be at 10. It gave me a DRAM frequency of 1604? So I thought that the UCLK with a multi of 20 should be at 3200 or 3208 (from1604)

I read that the UCLK frequency should be > or = to 2 x the DRAM frequency. But, the UCLK keeps showing up at a value slightly less than this. Like if the DRAM is 1604 the UCLK is 3207?!? I'm lost.

I thought I would try this out.

1604 DRAM.
3207 UCLK.
160 BCLK.
2880 QPI

CPU voltage 1.35v was told this need to be 1.20v-1.375v
DRAM bus voltage 1.65v what ram is rated at for voltage
QPI DRAM Core voltage 1.35v was told this needed to be 1.20v-1.40v and within .5v of DRAM bus

System ran for a while and then froze while playing a game.

I'm using a Corsair H70 water cooling unit for the CPU and it idles between 39C to 45C.

Anybody have any tips that would make the Overclocking experience a lot less confusing?

I don't want to have to spend $1000 on a 990x.
10 answers Last reply
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  1. I've been through an i7 920,i7965X and now an i7 990x. I have found the easiest way to overclock the i7 9xx series is to simply increase the cpu vcore and use the highest cpu muliplier then increase the BCLK until you hit the desired frequency.

    ex: 24x167 = 4.08GHz

    You will also need to increase the qpi voltage since increasing the BCLK requires more voltage to stabalize the overclock of the qpi. The rule of thumb is to keep the qpi voltage at about the same as the cpu Vcore. Leave everything on auto. I have read loads of overclock guides that have you changing the many of the settings without any solid justification as to why. The voltage range for that chip is 1.2-1.375V. That is the safe recommended range. There is another chart that intel has that shows the absolute range to be 1.2-1.6V. Exceeding 1.375V is supposed to degrade the lifespan of the chip. exceeding 1.6V is supposed to kill it fast. I have read that many people use up to 1.45V full time. I had my i7 965 running at 4GHz but it required 1.4125V in order to run prime95 stable.

    I would start with a cpu Vcore of 1.4V and a qpi voltage of 1.35V and run prime95. If you can make it through at least 20 minutes without one of the threads shutting down then you can try lowering the Vcore and doing it all over again until you find a Vcore that is 100% stable. Once you find a stable Vcore you can do the same for the qpi voltage. I don't think 1.35V is enough to run the i7 960 at 4GHz and be stable under load.
  2. ASUS provides a nice overlocking tool that allows you to change most of the BIOS settings while windows is running so it should be easy to adjust your settings to find a stable overclock. If the Vcore is close but not quite enough, one or more of the threads will shut down while running prime95. If the Vcore is too far off then your computer lock up or give you a BSOD. Also, your RAM should able to handle 1670MHz easily using a BCLK of 167. keep in mind that 1.4V may not be enough and you may have to slightly increase it. If you want to be sure you are stable then let prime95 run for 8 hours or so. You may find that your overclock is stable for 20 minutes or so but after a few hours an error is generated. If that is the case, increasing the Vcore by only one increment should fix this.


    One of the advantages of the 990X aside from the obvious 6 cores/12threads is the ability to run at 4.4GHz with a Vcore of 1.35V at a max temp of 65degrees under full load. I suspect your i7960 may approach 80 degrees while running prime95 at 4GHz. I would not be to worried about that temp since prime95 is a torture test and you will probably never run a program that causes that much of a load and generates that much heat. My 965X would hit 80 degrees under prime95 at 4GHz but it would barely hit 55 degrees after hours of playing bf3.
  3. I've read on many forums about using the highest cpu multiplier or lowering your cpu multiplier to find your highest bclk. I do not see any way to change the multiplier in the bios. I thought the multiplier on the 960 was locked?
  4. Cuzzin Chizzy said:
    I've read on many forums about using the highest cpu multiplier or lowering your cpu multiplier to find your highest bclk. I do not see any way to change the multiplier in the bios. I thought the multiplier on the 960 was locked?

    'Locked' simply means you are limited to a maximum multiplier. For example the i7 960 has a max mulitplier of 24. You can still still lower the multiplier but you cannot go any higher. Unlocked means you can adjust it to whatever you want. I read somewhere that the max muliplier on an unlocked i7 9xx is 60 but I have not been able to verify that. I will have to go home to check the BIOS on my ASUS board to see exactly what it is called but you need to change the 'cpu level'( I think that is what it is called) to manual from auto in order to gain access to the BCLK and multiplier. The easiest way to overclock is to use the highest multiplier with a lower BLCK since increasing the BCLK overclocks the motherboard and not just the processor. If you want to find out what the highest BLCK your motherboard can handle then use a lower multiplier and slowly increase the BCLK until the system crashes while keeping the over frequency close to the stock 3.2GHz. An example would be 17x180 = 3GHz. You can slowly increase the BCLK until the system crashes then you have found your max BCLK. You want to keep the cpu frequency lower since you don't want to confuse a crash from the BCLK with a crash from an overclocked cpu. The standard qpi which is basically the motherboard bus speed for socket 1366 is 4.8GT/s which roughly equals 2400MHz. That is derived from multilplying the BLCK by 36. So 133x36 = 4800GT/s. If you are running with a bclk of 167x24 for a cpu frequency of 4GHz then you have also increased the motherboard bus to 3000MHz. Depending on the quality of the motherboard, your overclock may fail due to the qpi being overclocked not nescesarily the cpu being overclocked. That is a big reason why unlocked multipliers are preferred.
  5. Back to the original question, you should be fine using 1604MHz for DRAM with a BCLK of 160 and multiplier of 24 for a cpu frequency of 3.84GHz. Leave the UCLK and QPI on auto. QPI voltage of 1.35 should be good enough but since you have the motherboard overclocked with a BCLK of 160, you may need to increase it slightly for stability. CPU vcore of 1.35 should do for 3.8GHz but you may need a small increase for stability. I would lower the cpu mulitiplier and keep the BCLK of 160 and run prime95 or OCCT or whatever you want to use to see if your system is stable. That will tell you the qpi of 1.35V is enough for the BCLK overclock. At this point, you can also start lowering the QPI untill the system crashes to find out how low you can run it. No need to have unessecary voltage generating heat in the cpu. Once you are happy with the BCLK frequnecy and voltage you can then go back to a mulitplier of 24 and play with the cpu vcore to get it stable.

    Good luck!
  6. So I found my BCLK max is 210. 220 gave a blue screen. I tested BCLK first then RAM second. Got RAM to 1680 or close but it was memtest86+ unstable at 1.64v and the next increment up was 1.656 v . Is slightly over the recommended 1.65v ok? Don't want to burn up the RAM.


    Oh and what are the advantages/disadvantages of using high multiplier or high BCLK?

    Should I go 20 x 200 or 25 x 160?

    Does higher BCLK give better performance than higher multiplier if they both come out to 4GHz?

    And doesn't high BCLK give higher temps/volts?

    Thanks for your help. Almost there.
  7. 1.656 is fine. That is what mine is set to. Higher BCLK will give higher temps because it needs higher volts to maintain stability. As far as cpu performance, it makes no difference how you get there 4GHz is 4GHz. A higher BCLK will give you a faster QPI which means your system bus is faster so it will theoretically give you better performance at the cost of increased heat, though the question is will a slightly faster qpi give a noticeable performance increase. That I cannot say. You will need to experiment with benchmarking to answer that.
  8. I currently have my bclk at 200. Seems stable.

    Set my RAM speed to 1604, and tried a dram voltage of 1.643v and 1.656v. Both ways gave errors in memtest86+
  9. Cuzzin Chizzy said:
    I currently have my bclk at 200. Seems stable.

    Set my RAM speed to 1604, and tried a dram voltage of 1.643v and 1.656v. Both ways gave errors in memtest86+

    I would check the RAM timings and make sure they match the manufacturer spec and if you still get errors try installing only one stick at a time to see which one is generating the errors. If the RAM timings and voltage are ok and you still get errors it is probably time to RMA the RAM.
  10. Hey everyone, here is a guide I used to OC my i7-960, takes time to read it all but definitely worth having a skim over if you're new to OC or just want to learn more. It surely helped me. http://www.overclockers.com/updated-intel-overclocking-guides/

    Got my OC to 4.23ghz (air cooled using Prolimatechs Megahalem REV.B heat sink - http://www.frostytech.com/articleview.cfm?articleID=2481)

    21x202 BCLK 1.325v with the help of that guide. Ran 8 passes of IntelBurn Test on Maximum with no error, picture shows 1 Pass only, couldn't be bothered running 8 passes again just for a screenshot since I missed it the first time round.

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