i have i5-760 with p55a-ud3 mobo, i have managed to downclock memory to 1040mhz by changing bclk and memory multiplier, my default bclk is 133mhz but i was only able to lower it to 130mhz because lower than that pc won't boot, or uncore frequency won't match ram speed. so is there away to go lower on bclk like 115mhz, even if i don't have to downclock ram ?!
What exactly are you trying to do and do you mind if I ask why? Why are you underclocking?
i am just underclocking and undervolting to see how much i can go low on volts, not to save power but for over all learning, just like overclocking but the opposite.
what i am trying to do is lower the bclk to reach 2.4ghz, i know i can use multiplier but i don't want to do that as cpu when idle it will lower only multiplier and not bclk. so if i want to decrease bclk but i hit a wall with ram frequency and uncore frequency as they don't match any more.
do you have any ideas you can help me with regarding my questions above ?
You might need to increase your memory multiplier to keep it running at a speed within its rated specifications. You could also try dropping voltages. BLCK over/underclocking is often much more limited than multiplier overclocking because many different parts of the computer base their frequencies on it, so it's not always possible to use the BLCK to underclock without making adjustments to some other parts to keep them either within their rated specifications, or attempt dropping voltage on them to hopefully have them run more stably at below their rated specifications. You might also be able to try tightening your RAM's timings if all else fails so that it isn't running at too high of a voltage for it's frequency and latency. Uncore might also need a drop in some CPU voltage settings.
Basically, if you underclock without lowering voltage as you go down, you're now overvolting the parts and that can hurt stability just as much as undervolting them for their frequency.
If you had an 2.66GHz CPU (stock) then maybe but since you have a 2.8GHz no. If you increase the Memory Multiplier above 12 then frankly -- whatever you're doing here makes ZERO sense.
The i5-760 can handle 'normally' DDR3-1600 or Memory Multiplier of 12 -- no other changes. The cutoff is 2.66GHz CPUs. Lowering the BCLK -- Who Knows!? Everything I've tried is 133.33MHz~160MHz~200MHz and not 100MHz~115MHz on an LGA 1366/1156.
You shouldn't need the uncore and memory frequency to be synced like that for stability on the i5-760, but I would recommend it, if possible, or to at least have the uncore frequency greater than 2:1 to the DRAM frequency.
my memory multiplier doesn't have x12(only x6, x8, x10), and only when i sync memory to uncore system restarts, so only in using x8. i have managed right now to lower bclk to 125mhz, which is 1000mhz for memory, system restarts but if i shut it down completly it won't start until clearing cmos. my motherboard lowest support is 1066mhz memory, below that system won't start and bios will load fail safe.
best confg. i got with everything stable is 1040mhz memory with 130bclk.
do you think there is an option in bios i should eneble or disable?
I still cannot figure out what in heck you're doing? I wouldn't lower BCLK and instead lower the CPU speed and/or Turbo and/or Hyper-Threading.
CPU Clock Ratio -> (Lower values) 18~20 2.4GHz~2.67GHz
Intel(R) Turbo Boost Tech. -> Disabled CPU Multi-Threading -> Disabled ; N/A to i5's.
That will neuter your CPU really good.
really sorry for bothering jaquith.
i have all c-states: on,
qpi clock ratio: x32,
memory performance enhance: turbo,
memory timnings: default(kingston ddr3 1333mhz),
load line calibration: off,
cpu vcore: normal,
vtt voltage: 1.05v,
pch core: auto,
cpu pll: 1.6v,
why i want to lower bclk becuase in overclocking we can make bclk higher, so why not in downclocking? what affects it?
Right-off, lowing the BCLK doesn't mean proportional Voltages can be dropped and in fact the opposite might need to be raised. Example, the DRAM Voltage of 1.5V, unless you have a 1.3V kit (DDR3L or DDR3U) is going to cause failures -- either in posting or errors which in-turn corrupts data and/or a BSOD.
Further, the Intel Voltage tables (cpu vcore: normal) might not be programmed into your BIOS for some oddball BCLK or which can also cause the CPU to drop-out so you might need to FIX the vCore.
So start with FIXING the voltages and assume the CPU voltage tables won't work with a <133.33MHz BCLK.