4820K OC help

[M11C]

Hello, first thread here (didn't have much luck on overclock.net)

so i need some help overclocking my i7 4820K.
it's an Ivy-E CPU with a 2011 socket, meaning it only works with the X79 chipset. it runs at 3.7GHz stock, 3.9 Boost.

Specs:
Mobo: R4BE
RAM: 4x 8GB G.Skill RipjawZ 2400MHz CL10
PSU: AX1200i
Cooling: EKFB R4BE monoblock

it runs completely stable at 4.5GHz at 1.2Vcore and LLC at high, as far as i can tell.

4.8GHz won't boot at 1.3Vcore, but i can get into windows at 1.35Vcore with CLL at Ultra, but Intel Burn Test fails after 2-3 passes.

i think i need to change some other voltages like VCCSA, VTT, PLL etc. but i have little idea what these voltages will do.

also, i'm not sure what RAM settings i need; i've just been running them at ~1000MHz when OC'ing.

is it safe to change CPU strap/ will it help get a stable OC?

will it help using quad channel memory, over dual channel?

is it recommended to use XMP?

i'm hoping to be able to do some benchmarks at 5.0GHz, but getting 4.8 stable is fine for now.

Btw. at 4.5GHz temp is at ~50C during stress testing.

- Thanks

[Nate152]

If you're not stable at 4.8GHz your cpu needs a little more vcore. Your temps are fine so go for it. To hit 5.0GHz you may need upwards of 1.50v.

No need to fool with any other voltages when overclocking your cpu.

[Korth]

XMP is basically just an "automatic" manufacturer's preset for memory timings. Always handy to use as a default. But serious overclockers will always tweak timings and try to push them a little faster. Specific details about timing and speeds aren't as important (to me) as total overall real-world memory bandwidth/throughput, there is just no substitute for "fastest possible" unless you're targeting an impressive spot on certain benchmarking high score lists.

The processor's iMC has limits, of course, and overclocking performance varies with each individual part. The X79 chip also has limits, but (unless you got a lemon mobo) this will have much less impact than the CPU. You may need to find an optimal balance of maximum-CPU-overclock vs maximum-DDR3-overclock because few processors are good enough to run both at extreme speeds simultaneously. You'll probably have to bump several voltages. Your watercooling should help a lot, but an i7-4820K at 4.8GHz pushes past the sweet spot (usually 4.2GHz-4.5GHz) - it will generate a lot of excess heat, it will be subject to sudden and dramatic failure (instability). If your cooling is up to the task and you can live with the odd BSoD (maybe once every hour or three) then go for it, otherwise you'll have to throttle down a few notches or upgrade to faster parts.

Best practice is to overclock a single component at a time. In careful, conservative increments working from bottom upwards until you notice instabilities. Reconfiguring everything over stock all at once is reckless and uncertain.

[M11C]

@Nate152, finally a responce, thank you.

yeah, i expected i would need around 1.5 for 5GHz.

this weekend i've only worked on my 24/7 clock.
i am now runnig, for 24/7, 4.1GHz at 1.088 Vcore with -0.14 offset, giving 0.688V at idle

there are still a few sitting i want to mess around with for 4.8GHz at 1.35 Vcore, like VCCSA, PPL, power phase control, LLC, current capability, and possible VTT.

otherwise i think it wouldn't be a problem at 1.4 Vcore.

right now at 4.1GHz i'm running VCCSA at 1.075 (goes up to 1.1) and VTT at 1.1, wich seems a bit low, but it seems to be stable 😛

i'm just happy that my 4x 8GB 2400MHz RAM kit seems stable at 4.5GHz 😄

[Nate152]

vccsa is for instability of high speed ram, if your ram is stable you don't need to fool with this. I know our boards and cpu's are not the same but I had to set the vccsa voltage to 1.275v to get my ram stable at 2800MHz.


Vcore as you know needs to be bumped up for stability when overclocking your cpu.

LLC helps with vdroop and medium is the preferred setting, if you use ultra high or extreme it will overshoot the vcore you set.

Setting the cpu current capability as high as it will go will also help with overclocking your cpu.

This is all I have played with on my board and my cpu is running at 5.0 GHz with 1.45v

[M11C]

Nate152 wrote:
vccsa is for instability of high speed ram, if your ram is stable you don't need to fool with this. I know our boards and cpu's are not the same but I had to set the vccsa voltage to 1.275v to get my ram stable at 2800MHz.


Vcore as you know needs to be bumped up for stability when overclocking your cpu.

LLC helps with vdroop and medium is the preferred setting, if you use ultra high or extreme it will overshoot the vcore you set.

Setting the cpu current capability as high as it will go will also help with overclocking your cpu.

This is all I have played with on my board and my cpu is running at 5.0 GHz with 1.45v

yeah, that's why i thought it was a bit odd that i didn't need higher VCCSA.

right now i have LLC at 75%, wich is recommended for offset.

current capability is at 120% bevause i need Power Phase Control set to optimized. higher and it automatically get set to extreme.

WOW, pretty sick temps. and considering it's the older generation Ivy it's pretty impressive that you don't need more Vcore.

but like i said i'm still tinkering with it, and this PC is actually my first experience with OC'ing.

[Nate152]

Hmmm not sure what happened to your post but read mine above please.

[Nate152]

If you're shooting for 5.0GHz you could set the power phase to extreme but this will also make temps rise a little.

[M11C]

Nate152 wrote:
If you're shooting for 5.0GHz you could set the power phase to extreme but this will also make temps rise a little.

yeah, buti have lots of temperature headroom, wich is why i wanted to try juicing some other voltages.

thought i'd post a screenie.

[Nate152]

yeah you have very good temps and the temperature controls how far you can overclock your cpu. Stress testing temps will always be higher than your gaming temps. You don't want to see gaming temps over 75c although the lower the better but stress testing temps can sometimes hit 90c+. It just depends what you're going for and how good your cooling is. It seems you have good cooling and can probably hit 5.0GHz.

One thing, there is a point where our cpu's will hit a wall and will need ALOT more voltage to hit the next 100MHz. I don't know if I'm at the wall or not this is the highest I've taken this cpu. But just be aware of it in case you find your cpu needing a lot of voltage and not becoming stable.