How to Overclock a (locked) Sandy Bridge E

So, basically there are two BCLK multipliers available: 1,25x and 1,66x. The BCLK overclocking capabilities seem to be slightly better too (95.1MHz BCLK -> 115MHz BCLK?), which would bring us 95-140MHz and 160-190MHz ranges to play with. All-in-all, it seems that the OC finetuning capabilities are back with these chips; the only question that remains is whether or not the clock walls. are still present.

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Without an unlocked multiplier on an LGA1155 system, you’re limited to Base Clock overclocking, which Intel only recommends increasing by up to 5 per cent, while others claim it’s only good for up to a 10 per cent boost.

Thankfully, we now know that Sandy Bridge E systems support more flexible Base Clock overclocking than Sandy Bridge systems. The key is a new divider between the Base Clock of the system and the CPU – it’s a gearing mechanism, just like a memory strap or a CPU multiplier. There are two dividers to tweak, at 1.25x and 1.66x, with both acting to gear up the Base Clock used by the CPU, while leaving the Base Clock for the rest of the system alone. Having two Base Clocks in one system will probably get confusing, though, so in the absence of clear labelling from Intel we’ll call them the System Clock and the CPU clock.

You’ll also need to tinker with the Turbo Boost tweaks with which you're familiar when overclocking a Sandy Bridge system – increasing the maximum possible power draw of the CPU to prevent Turbo Boost capping your overclock, or reducing it during a prolonged session.

Let’s say we’re aiming for an overclock of 5GHz (something that the Intel engineers said they had achieved during a bit of mucking around in their office). We don’t know how much of an overclock that is, but we know that 50x100MHz=5GHz. However, if we have a ‘locked’ Sandy Bridge E CPU that doesn’t have a multiplier of 50 or more, we’ll have to change the System Clock and the CPU divider instead. The maths requires us to work backwards from 5GHz like this:

  • 1) 5,000 ÷ 1.66 = 3,012
  • 2) 3,012 ÷ 100 = 30.012
  • 3) 3,012 ÷ 30 = 100.4


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Belgium Massman says:

In the original article at Bit-tech, the author mentions the CPUs are limited by TDP and the user will have to fiddle with turbo modes to achieve higher clocks. Don't panic just yet: this was also the case with the first generation Core i7 (Bloomfield). Mainboard manufacturers found a way to work around the TDP limitation; which is probably going to happen again with SB-E.

Btw, anyone notices the Internal PLL Override setting in the picture attached to the news item? It's enabled, which makes me fear there's not going to be another BIOS trick to increase the maximum OC headroom for the SB-E like there was for SB when it launched.

Which means 5.3G. Or 6G if you bin a thousand.

Germany SoF says:

The ES seem to be unlocked so far but 5.5 wall again?

Belgium Massman says:

Rumours say SB-E = SB minus 200MHz. It's X6800 vs QX6700; E8600 vs QX9650.

Germany SoF says:

So what are we doing next? Searching a new hobby? :D

K404 says:

Maybe holding on to my 990X wasn't such a dumb idea after all

Belgium Massman says:

You're right Kenny ... :( Maybe we can Bulldozer our misery away?

K404 says:

I dunno how many benches BD will be good in, but I DO expect benching it to be a lot more fun than SB/ SB-E

Spain Predator says:

Does it mean SB-E won't have CPUs with unlocked multiplier or what? :S

United States dumo says:

Better hold on tight to your 58X/59X chip...for now

Czech Republic OBR says:

1. Yes, SBE = SB-200 MHz on air ...
2. Coolaler has pretty old sample, stepping 5 ... now is 7 and higher
3. ive seen more BCLK multis then 1.25/1.66 ...
4. Coolalers 5.5 was made under dice ...

United States dumo says:

Do you have any bench result OBR?

Czech Republic OBR says:

no, have 2x 3960X at home and one "K" on the way ... but no board yet ...

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