Overclocking voltage

[cryptz]

I just wanted to ask what those of you that have a 3960x and are running at 5ghz + have your voltages set to. Currently I am using speed step 6 core 50x multiplier (100.100 bclk) but i have my voltage set at 1.485. This may be high but was necessary to get prime stable. Lower voltages seem to decrease the time i can run prime before i blue screen. Temps are fairly good ~61.0 C

At 1.485 in the bios Asus's Probe II only reports a vcore of 1.448-1.456 under load, so i am actually dropping while under load and at the set rate when idle. I will double check for a vdroop setting (kinda remember that being the solution on older boards but i honestly didnt see it when i looked). Before i upped the voltage i would see the mouse get "sticky" and then a blue screen. There may be other settings i could adjust other then vcore to resolve this problem, if so please let me know any suggestions. I am still not really 100% stable, i can run prime for about 20-30 minues but then i will notice maybe 1-2 cores not being utilized and then it will blue screen. any suggestions welcome. I may just need to dial 6x down a notch

[cryptz]

looks like cpu llc was what i was after, i changed my vcore back to 1.465 and retesting, let me know if you have any other suggestions though.

[cryptz]

i am currently running a vcore of 1.385 and llc set to extreme. I am watercooling the vrm so it seems to work.

is there any reason this isnt ideal? i basically need 1.48 volts when all 6 cores are maxed. It would seem that any other voltage combination is going to put me extremely high at idle/low workload. These settinsg keep me around 1.40 for single threaded apps, about 1.45 for 4 cores and 1.48 for 6 cores @ 5ghz which seems to be about what i need to be stable anyways. my only concern is that even with a waterblock the vrm area is getting very hot. I actually saw it throttle once at 70c cpu temp after about 25 minutes of 12 threads of prime, but the honest truth is i wont ever be maxing 6 cores for 25 minutes.

[cryptz]

I wanted to post 1 more time because I like talking to myself but also because I finally got this where it needs to be and I think maybe some people can benefit from my trial and error.

essentially I opted to use speed step because most of the time I can keep the clocks down if I am not doing anything, also speed step has a nice feature of only overclocking active cores, so the # of threads becomes extremely relevant to your power draw.

By using speed step I knew I wanted to scale my power out a bit. I determined early that I could run stable at 1.48v when maxing out all 6 cores. It seemed like a bad idea to just set vcore to 1.48 and forget it since most of the time I wouldn’t need that much power. I also quickly learned that having CPU llc set to medium would result in not enough power if vcore was set to 1.48. You can increase CPU LLC to high and it will generally hold a vcore rating of 1.46 or higher.

That all being said I wanted to scale my voltage with clock speed. My initial attempt was to set the vcore low but make CPU LLC extreme so that it was actually adding power with clock. This worked but it lead to VRM overheating and throttling my CPU. I was water-cooling the VRM but still throttling so I had to abandon that idea.

My next attempt was to go with a vcore offset of .080 and put LLC to high. This put me right at 1.48v under 12 thread load at 5 GHz. This worked great and I was able to run stable. Since I really am unable to monitor VRM temp directly I decided to shoot for CPU LLC to medium to be safe. That resulted in my vcore voltage being 1.46 under 12 thread load at 5 GHz which resulted in eventual blue screen. (Generally I see a prime thread stall, 1 CPU under clock, and then it blue screens.

I went back into the bios and set my vcore offset to + .125 and left LLC at medium. This resulted in 1.48 under 12 thread load as well as good idle voltage (under 1.0v at idle). I can only assume that my VRM is lower this way, the CPU temp difference is non-existent.

I would be happy to share any specific bios settings. I don’t see many people talking about overclocking this way on the forums but it seems like the best of both worlds to me. I find that if I shoot for a number of prime threads somewhere in the middle the voltage is also in the middle and adequate. For example I can run 6 prime threads at 1.43 volts stable @ 5 GHz and it adjusts the voltages automatically. My hope is that it leads to a longer processor life, but for all I know all of the switching could be harder on it =)

So to sumarize what I think is a good strategy with dynamic clocking and dynamic voltage:

1. Determine Vcore necessary for max overclock - do this with a manual vcore setting and high LLC
2. Change CPU LLC to medium to reduce VRM temp.
3. Test VCore offset under load to determine what lands you at necessary Vcore max voltage while testing.

Generally i think you will find all of the clocks/voltages in the middle fall into place.

[mdzcpa]

You've posted some good info here.

if you go back to the postings in November and December, you will see a number of posts similar to yours by myself, 8 Pack, and a few other guys that we made while we were working on our overclocks.

I find that your results are very similar to my own. I run LLC Medium and V core offset of 1.15v resulting Vore of 1.475v for my 5Ghz overclock. LLC of Extreme is not a good idea unless you are super cooling sub ambient. I am also watercooling the VRMs with a Koolance block and found Medium to be best. High can work, but I lower by Offset to .950.

Another reason I run LLC at Medium is that even with the waterblocks, cooler VRMs keep the CPU socket area cooler and overall temps down. I can get my CPU to 5.1Ghz stable, but it requires LLC of High to do it.

Although you figured most of this out on your own in a short period, you are right on track with results that mirror mine almost dead on.

[HiVizMan]

Cheers cryptz for posting up your work log, that is pretty much what it turned out to be. I have no idea how I missed your first post two days ago, besides the fact I was asleep of course, but seriously do not recall seeing your original post at all.

The one key pointer I would add to your thinking is cooling the VRM's if you are going to be loading hem up when you over clock. The control circuit on the VRMs will kick in and throttle your CPU if the VRM's get too warm, I know of heaps of folks who think they are happily running at 5.2GHz but performance has been throttled and they would be better off at 4.6 or 4.8GHz.

Keep it up mate good work.

[cryptz]

vrm is definately important and i did verify it is no longer throttling. Running the CPU LLC at medium + watercooling the VRM definately keeps my VRM temps in check.

[HiVizMan]

Outstanding to hear that.