I have a question about system overclocking

[jtomaskovich]

Good Evening,

 

This is my first post on the LTT forums, glad to be here! If the CPU is running based off of a clock multiplier, and the motherboard system clock is, say, 100MHz, why can't we just overclock the system clock to 200MHz and not have to put as much stress on the CPU?

[WhitetailAni]

6 minutes ago, jtomaskovich said:

Good Evening,

 

This is my first post on the LTT forums, glad to be here! If the CPU is running based off of a clock multiplier, and the motherboard system clock is, say, 100MHz, why can't we just overclock the system clock to 200MHz and not have to put as much stress on the CPU?

That is something that is done, but in the end the CPU runs at the clock speed of base clock x multiplier, plus raising the base clock too far can have weird side effects.

[LIGISTX]

7 minutes ago, jtomaskovich said:

Good Evening,

 

This is my first post on the LTT forums, glad to be here! If the CPU is running based off of a clock multiplier, and the motherboard system clock is, say, 100MHz, why can't we just overclock the system clock to 200MHz and not have to put as much stress on the CPU?

Welcome to the forum! Its a fun place to be

 

This question is likely deeper than you anticipated, but the short version is, the CPU's speed is a combination of the base clock and multiplier. You CAN up the base clock, but most CPU's these days really, really don't like that - to be fair, not many CPU's have loved it over the years, but some have tolerated it a lot more then others, with a few exceptions that actually benefited greatly from a base clock OC.

 

BUT, it is just as stressful on the CPU. The final GHz is the final GHz, doesn't matter if you get there with a 5ghz base clock and a 1x multiplier, or a 100Mhz base with a 50x multiplier. The CPU is running at 5Ghz either way, and its going to need the voltage it needs to do that.

 

Where the "depth" to this question is brought in is the rest of the system ALSO runs on this base clock... RAM speeds are what they are as a function of the base clock. So if you up your base clock 1% from 100 to 101, you also up your RAM speed from say 3000 to 3030. And your PCIe also runs at 100hz base clock, so that ends up a little faster as well. At least, this is how it worked a few years ago, tbh its possible Zen and newer Intel has more separation between CPU and the rest of the system since north bridges are getting exceedingly "less smart" and south bridges no longer exist.

 

But, TLDR; you can OC with a base clock OC, but it isn't really any easier on the CPU, and it may be harder on other things. The last system I did this with was my i7 920, I ran a slightly faster bus speed then stock IIRC. Its been... oh, like, 12 years? lol. These days tho, not much point in it especially since multipliers are unlocked, multiplier OCing is WAY easier.

[Guest]

21 minutes ago, jtomaskovich said:

Good Evening,

why can't we just overclock the system clock to 200MHz and not have to put as much stress on the CPU?

The Reference frequency, also commonly referred to as FSB or bus frequency, is bound to the I/O which is your Sata controller, formerly known as a chipset. When you increase this, it may very well corrupt your drive. Just depends if you push to much too far.

 

Way back on DDR SD RAM, (ddr1) there where some boards that where like this. Linked at 200 FSB. Usually the VIA chipset boards. So the gamers and overclockers would buy the NForce chipsets which where not tied to the chipset. Made overclocking much more fun. Capable of 100% bus clocks increase meaning 200mhz to over 400mhz. 

 

However running a cpu with a reference clock even twice that of stock makes no real performance difference at all for most practical benchmarking. So even though it looks cool, (TLDR) it doesn't produce anything other than a different way to generate a clock frequency.