Baseclock underclocking

[Cereal5]

Hey LTT,

 

In one of Linus' videos on overclocking an X99 CPU, after pushing the modifier up as high as stable, he pushed the baseclock up to I believe 105. However, on Haswell-e, I don't remember the term, but it's tied into the motherboard and overclocks everything, like the SATA bus, RAM etc. I don't know how much damage overclocking your HDD can do, but would it be possible, instead of pushing the baseclock up, to turn the baseclock down to say 94 or 95 and turn the CPU modifier up higher?

 

Example: My 5820K is stable at 4.3GHz but gets iffy at 4.4. With the modifier at 43, I could turn the baseclock up to 101 or 101.1 and get 4343 or 4347 MHz respectively. What I'm proposing is to set the modifier at 44 and turn the baseclock down to 99 or 98.9, giving me 4353 or 4357 MHz respectively. Is turning the baseclock down below 100 even possible? (i have not checked the BIOS). If so, would it even be recommended, since it would theoretically decrease speeds across the system?

 

P.S. I know, I got like a 30th percentile chip. 4.3 GHz @ 1.286v is pretty bad, and temps on the two hottest cores max out around 84. One day I plan on getting a 6850K as a stop gap to a full rebuild and hopefully I can OC to my hearts content then. Or maybe a custom loop. You should probably ignore this, I don't want to start the "when should I rebuild and what should I buy" conversation.

Also, this is the video I was referring to: 

 

[Jurrunio]

48 minutes ago, Cereal5 said:

how much damage overclocking your HDD can do

this is where something goes wrong. Pushing BCLK has no effect on the HDD's operation, just how the SATA interface pulls data from it. Therefore raising BCLK to sky high levels doesnt affect HDD's lifespan, it just breaks stability at most.

 

48 minutes ago, Cereal5 said:

I don't remember the term, but it's tied into the motherboard and overclocks everything, like the SATA bus, RAM etc

No specific term to that, just 'BCLK tied to PCIe frequency' or sth similar.

 

However, this usually isnt a problem for X99 (or HEDT platform in general) since boards this high end usually have a clock gen chip, which allows them to bypass the stupif BCLK tied to PCIe thing. Some Z series and X series chipset boards for the consumer CPUs (like Z370 and X470) also come with clock gen chips.

[Cereal5]

5 minutes ago, Jurrunio said:

However, this usually isnt a problem for X99 (or HEDT platform in general) since boards this high end usually have a clock gen chip, which allows them to bypass the stupif BCLK tied to PCIe thing. Some Z series and X series chipset boards for the consumer CPUs (like Z370 and X470) also come with clock gen chips.

Hm, I feel like that was only introduced in Skylake, I remember hearing something about the baseclock being separated from other buses and only affecting the CPU, and that's when the whole "overclock your locked CPU on an H110 board" craze went on.

[Bananasplit_00]

If your board has a clock gen on it then feel free to mess around all you want, but not all Z/X series boards have them. Mine dosent and something gets WILDLY unhappy once I move it more than a megahertz and my system gets unstable even with no overclocks otherwise. But yes it is possible to underclock BCLK at least on some boards. I don't know if its a common feature but you should be able to set it from like 50-200 MHz or something like that.