Core and Uncore ratio doubts

wsarahan · Oct 3, 2015

Hi guys how are you?

I have a doubt here, i have an i7 4770k @ 4.5 with 1.3vcore

I was looking at bios trying to increase something and saw that my uncore ratio was set to auto, and the bios suggest that the uncore be the same or higher than core ratio

is it true? Should i put auto off and set the uncore to 45 as well? Will i have some real gain? Can happen any issue like instability?

Edit: Another question, I`m using 1.31 vcore to 4.6, do you think i can reach a stable Oc with less? I know that the basically to more than 4.5 we will need something about 1.3 to more right? Or am i wrong?

TechyInAZ · Oct 3, 2015

uncore or ring bus or cache ratio (lots of names for it I know) is the cache speed on the CPU. ONLY overclock the uncore once you get solid stability on your CPU overclock. Then overclock the cache to, if possible, the same speed as your core clock.

However, uncore is completely unnecessary to overclock if you don't want to mess around with it. It will only bring a very minor bump in performance.

wsarahan · Oct 3, 2015

TechyInAZ :

Thanks man you are right

I just bumped the uncore to 45 directly and the pc freezed

And I have another question here if you can help me

I' m using 1.31v to reach 4.6 is this a normal vcore for it? Do you think I can get stable with low? Searching the Internet I can see the the main 4770k need something more that 1.3 when talking about 4.5 or more

An I wrong?

Thanks again

PhysX_HW · Oct 3, 2015

You can set 1.30Vcore and then rum prime95 for like 12 hours, if you don't have any errors, you can decrease the voltage even further, but I wouldn't worry about that. If you can cool it adequately, you should be fine.

philipew · Oct 1, 2016

Keep the Uncore Ratio at 100 MHz below the CPU Core Ratio. For example, Core / Uncore at 4.7 / 4.6 - 4.6 / 4.5 - 4.5 / 4.4, etc...

philipew · Oct 1, 2016

wsarahan :

EXPLANATION
UNCORE (= not core, not CPU) is easy to set. This post is valid for Skylake 6600k / 6700k on any motherboard (Gigabyte, Asus, etc.). Among other things, the Uncore Ratio relates to the frequency of the cache used by the CPU. And you have to manually set the Uncore Ratio in the BIOS of the motherboard because it remains stuck at the stock ratio of 35 (3.5 GHz) even after you have overclocked the CPU Clock Ratio way above that. To do that my Gigabyte z170 motherboard indicates to set the Uncore Ratio equal to or higher than CPU clock ratio. And they are right ! ;-)

Ideally the Uncore ratio should be the same as the core ratio (as it is at stock values) or (particularly in the case of overclocking) higher than the clock ratio to not constitute a bottleneck. On my Intel i5 6600K I set the Core at 46 (4.6 GHz) and the Uncore at 49 (4.9 GHz) - yes, much higher than the Core! I tested it stable on a 2H Prime95 Blend test up to Uncore 52 and could probably go beyond that value but the overall performance drops after 49, so that's what I use.
To measure performance I measure the time it takes for the system to complete the Prime95 800K test on the four workers. Setting the Uncore ratio at 49 rather than 40 shortens the time by some 7 minutes (from 48 min. to 41 min.). Getting 7 minutes shaved off on 48 is getting 14.5% of raw processing (computational) performance gain! It does not change the Temp. and Power significantly from 40 to 49 (topping at 84 C max under 26 C ambient and 104.5 W) although I had to up VCore from 1.355 V to 1.390 V to ensure stability. The stability of the PC (BSODs, hanging, etc.) is also much greater, in fact rock solid (never had any trouble ever since). It is so good that I really feel it.
Games that would usually get the 4 cores at (for example) 96-98-100-97%, now leave them at 83-85-93-84%, further showing the overall gain in CPU performance. THIS IS ABSOLUTELY FANTASTIC !!! ;-)

philipew · Oct 1, 2016

I am now running my 6600K at 4.6 GHz after manually setting VCore at 1.380 V in the BIOS. With this, I set the Uncore Ratio (cache) to "49" (or 4.9 GHz) - yes, much higher than the Core ratio! It is mighty stable under anything Prime95 can throw at it and for as long as I want...

Here are details of my current, and ultra stable/safe, BIOS settings for i5 6600K on Gigabyte GA-Z170XP-SLI:
[1] - CPU Core Ratio: 46
[2] - FCLK Frequency For Early Power: 1 GHz
[3] - Uncore Ratio: 49
[4] - CPU Flex Override: Disabled
[5] - Intel Turbo Boost Technology: Disabled
[6] - CPU Enhanced Halt (C1E): Disabled
[7] - C6/C7 State Support: Disabled
[8] - C8 State Support: Disabled
[9] - CPU Thermal Monitor: Enabled
[10]-CPU EIST Function: Enabled
[11]-Voltage Optimization: Enabled
[12]-Residency State Registration (RSR): Disabled
[13]-Hardware Prefetcher: Enabled
[14]-Adjacent Cache Line Prefetch: Enabled
[15]-Extreme Memory Profile (X.M.P.): Profile 1
[16]-System Memory Multiplier: 32
[17]-Memory Enhancement Settings: Relax OC
[18]-Channel Interleaving: Enabled
[19]-Rank Interleaving: Enabled
[20]-CAS Latency: 15
[21]-tRCD: 17
[22]-tRP: 17
[23]-tRAS: 28
[24]-Command Rate (tCMD): 1
[25]-CPU VCore Loadline Calibration (LLC): High
[26]-CPU VCore: 1.380V
[27]-CPU VCCIO: Auto
[28]-CPU System Agent Voltage: Auto
[29]-PCH Core: Auto
[30]-DRAM Voltage (CH A/B): 1.360 V
[31]-Internal Graphics: Disabled

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Core and Uncore ratio doubts

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