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CPU cache whats the deal?

MatsGlobetrotte
Level 10
Hi,I got my maximus VI formula up and running nicely on 4.6 ghz full time. It requires a bit of voltage to be stabile but i can keep the temperatures reasonable with my watercooling system.Meanwhile i have so far not really found a way to understand how to tweak the CPU cache. In the carious modes of tuning i get it to multiplier 42 and then ...Is there a trick with voltages for it compared with the CPU or what would a normal maximum be when doing general OC with a lower end watercooling system. Meaning i dont have a massive amount of radiatorsAny help wouöd be appreciated
It started with a VIC-20... and now it is. Maximus Formula VI Intel 4770K 4.6GHz ASUS GTX780Ti 3GB Corsair Platinum Dominator 16GB 2400MHz Raid Express 240GB Samsung EVO 512 GB SSD Corsair 900D EK watercooling Corsair RM1000 ASUS PB278Q



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jab383
Level 13
Cache tweaking is a little tricky -- not as straight forward as core OC.

First, the Cache/uncore/ring (it has been called various things over the generations of CPU) is a very small part of a four-core processor. Any voltage that works will contribute very little power or heat and should have no impact at all on an otherwise adequate cooling rig.

All Haswells are different. I'll tell some things about what I've found, but check them yourself. For the same clock, cache needs a little more voltage than core. My current CPU cache voltage about what Vcore would be for 100MHz faster clock. The following are points I tested for full OCCT 24/7 stability:
Core: 4.4GHz at 1.18v; 4.6GHz at 1.29v; 4.7GHz at 1.37v
Cache: 4.2GHz at 1.13v; 4.4GHz at 1.22v; 4.6GHz at 1.36

How to find lowest voltage for stability at a given cache speed: Set core speed equal or greater -- there is no benefit from cache speed higher than core and cache running as much as 300MHz slower than core still works well. Add 0.05v or so the Vcore -- to add margin and keep the core out of the stability equation. Set cache voltage somewhat higher than what core would need. Run stability test of your choice, I use OCCT. If it passes, lower cache voltage, rinse and repeat. The real trick is to set everything else with a little margin so cache is the only factor near the edge of stability.

I'm running two profiles:
4.4GHz core at 1.18Vcore with 4.2GHz cache at 1.13Vcache, OCCT stable for 24/7 use.

4.8GHz at 1.52Vcore with 4.6GHz cache at 1.36Vcache, boots but needs 1.55Vcore applied in the OS for Realbench stability. This profile has even cranked up to 5.05GHz for some single-thread benchmarks.

Note cache running lower than core speed. I haven't found much improvement in any benchmark with higher cache clocks.

Jeff

MatsGlobetrotte
Level 10
Thanks for the good info jeff. Will test it out. Atleast i have startingpoint now:-)
It started with a VIC-20... and now it is. Maximus Formula VI Intel 4770K 4.6GHz ASUS GTX780Ti 3GB Corsair Platinum Dominator 16GB 2400MHz Raid Express 240GB Samsung EVO 512 GB SSD Corsair 900D EK watercooling Corsair RM1000 ASUS PB278Q