What is bclk ocerclocking

[saadgamer_17]

What is bclk overclocking .i heard this term first time.

 

[elbert]

Its raising the motherboards clock from 100 to at most 104 to get over a 100Mhz CPU increase in speed. This is mostly Intels limits to bclk OC but AMD's should do way more. Its old school overclocking and harder to get stable.

 

[TechyInAZ]

The Base Clock or BCLK in a motherboard is the clock speed that drives a lot of things on the motherboard, from system RAM to the CPU, and also PCIE devices.

Base Clock overclocking is where you can overclock CPUs and memory via manual manipulation of the base clock multiplier. The only drawback of this kind of overclocking is that it greatly increases instability of not just your CPU, but your memory and quite possibly your PCIE lanes which would be a mess.

BCLK overclocking has come a far ways though, certain motherboards can isolate the BCLK so only your CPU and RAM are being overclocked.

However, if your thinking of doing BCLK overclocking on Skylake or Haswell, I don't recommend it. 1, The BCLK multiplier doesn't go very high before getting unstable, 2, it's much easier to just overclock via multiplier on the CPU if you only want your CPU overclocked.

 

[philipew]

What is bclk overclocking .i heard this term first time.

As written here, BCLK is the base clock (set by default at 100 MHz) used to determine the frequency for the CPU, the FCLK, Uncore (Cache), and the MEMory. These four use their own multiplier of the BCLK frequency. For example the CPU Ratio would use 46 to get 46 x 100 = 4600 MHz (4.6 GHz), FCLK would use 10 to get 10 x 100 = 1000 MHz (1 GHz), the Uncore (Cache) ratio would use 45 to get 45 x 100 = 4500 MHz (4.5 GHz) and the MEMory would use 32 to get 32 x100 = 3200 MHz.

So if you increase the frequency of BCLK you immediately increase the frequency of CPU, FCLK, Cache and MEM. That's what I call "presto" overclocking. However, one should not get carried away with increasing BCLK. Past 2-3 % of increase (from 100 MHz) it's better (and more stable/accurate) to simply adjust the respective multiplier of the four (CPU, FCLK, Uncore (Cache), and MEM). For me BCLK is best for "fine" tuning because it shouldn't be increased much, mostly for stability reasons.

So when/how can it be used beneficially ? Well, here is my own example: I can do 4.6 GHz (multiplier 46) but not 4.7 GHz (multiplier 47) because my budget air cooling can't quite keep up with it overtime (especially in the Australian summer with an ambient temp. of 32 C). And although I could manage 4.65 GHz (half-way through), I can't set the CPU Ratio (multiplier) to 46.5 either (decimals are not possible for this). So I turned to BCLK which by the way accepts decimals like 101.09, 101.1, etc. By setting BCLK at 101.1 without changing any of the multipliers I get: CPU Ratio 46 x 101.1 = 4650 MHz (Bingo !), FCLK 10 x 101.1 = 1011 MHz (some benefits here too for latency), Uncore (Cache) 45 x 101.1 = 4549 MHz, and MEM 32 x 101.1 = 3235 MHz (minor benefits here but still some).

Of course you may have to adjust other things a little, like if your MEM cannot go over 3200 for example, then you reduce its multiplier to 31 to get 31 x 101.1 = 3134 MHz (won't even notice a difference in games), and of course you would have to increase CPU Vcore voltage to say 1.380 V (for my i5 6600K CPU) to cope with the higher frequency (doing it via BCLK doesn't change this... I wished). But my goal of reaching 46.5 GHz is achieved, and rather "elegantly" (= no sweat).

Better still!!! I have been running for the past few weeks at 4.65 GHz with Bclk at 103.34 MHz - using Vcore of 1.390 V to get the 1.380 V - 1.392 V operating range, multipliers Core/Uncore/Mem at 45/40/31 giving me in MHz 4650/4133/3203. Natuarlly, Fclk is at 1033 MHz. The performance increase with these settings (4.65 GHz CPU) is noticeable and the rig is extra stable. I think that Vcore at 1.380 V may already be sufficient (it's almost fully stable on Prime95) but the 12 mV extra to the next range above gives it extra "oomph" and stability under load in particular. It gives me great temps too... love it like that and won't change anything. This is a great setting and an excellent illustration on how useful Bclk tuning can sometime be..

N. B. Running Core/Uncore at a ratio of 1:1 will cost you 30 to 50 mV more in CPU Vcore (meaning a lot more heat) and is hardly worth the extra performance (if any).

My settings 6600K on Gigabyte Z170XP SLI LGA1151 DDR4 ATX:
[1]- CPU Core Ratio: 45 = 4650 MHz
[2]- CPU Base Clock (Bclk): 103.34 MHz
[3]- FCLK Frequency For Early Power: 1 GHz (x10)
[4]- Uncore Ratio: 40 = 4133 MHz (= 515 MHz below Core)
[5]- CPU Flex Override: Disabled <--- 1/4
[6]- Intel Turbo Boost Technology: Disabled <--- 2/4
[7]- CPU Thermal Monitor: Enabled <----------- 1/7
[8]- CPU EIST Function: Enabled <----------- 2/7
[9]- Voltage Optimization: Enabled <----------- 3/7
[10]-Residency State Registration (RSR): Disabled <--- 3/4
[11]-Hardware Prefetcher: Enabled <----------- 4/7
[12]-Adjacent Cache Line Prefetch: Enabled <----------- 5/7
[13]-Extreme Memory Profile (X.M.P.): Profile 1
[14]-System Memory Multiplier: 31 = 3203 MHz
[15]-Memory Enhancement Settings: Relax OC
[16]-Channel Interleaving: Enabled <----------- 6/7
[17]-Rank Interleaving: Enabled <----------- 7/7
[18]-CAS Latency: 15
[19]-tRCD: 17
[20]-tRP: 17
[21]-tRAS: 28
[22]-Command Rate (tCMD): 1
[23]-CPU VCore Loadline Calibration (LLC): High
[24]-CPU VCore: 1.390 V
[25]-CPU VCCIO: Normal <-------
[26]-CPU System Agent Voltage: Normal <-------
[27]-PCH Core: Normal <-------
[28]-DRAM Voltage (CH A/B): 1.360 V
[29]-Internal Graphics: Disabled <--- 4/4

The whole point here though is that I started from 4.6 GHz, which was already my "fully" stable overclock. BCLK was used merely for "refinement", not for initial (major) overclocking. IMO this is the best way to use BCLK with its ability to accept decimals (which is consistent with its "fine tuning" purpose). As I wrote above, beyond say a 2-3% increase of BCLK (from 100 MHz), it is preferable to use the CPU multiplier instead (going higher faster without also requiring major multiplier adjustments) and then close in with BCLK only for fine tuning "at the finish".

Of course this is more for "hardcore" overclockers (I prefer "enthusiasts") because frankly 4.6 GHz or 4.65GHz really doesn't make much difference at all for playing games (except that the temp. is clearly higher). But it's there for the taking.

Keeping things simple should always be part of any valid solution (for everything in life). Go easy on your OC and you will also enjoy it ;-).

By the way, I just found something similar done here, under "What to expect?" ("...which we increased more to 4750 MHz with a bClk of 101 MHz"):
https://uk.hardware.info/reviews/6513/9/how-to-overclock-skylake-processors-fase-2-bclk-en-geheugen