Question What is CPU multiplier?

TheFlash1300

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Mar 15, 2022
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I see a CPU report that says this:

"Multiplier: Current: 19 / Min: 11 / Max: 22"

So, what is a multiplier, and what happens if I increase it? Is it possible to increase it and will this increase the power of the CPU? The CPU is AMD-A4 9120e.
 
A cpu runs on a multiple of the system bus which is running at 100Mhz, so 19 times 100 would be 1.9Ghz 11 is 1.1Ghz and 22 is 2.2Ghz it changes to conserve battery life/power draw.

Yes the higher the multiplier the more power it uses and the faster it gets.
I don't think your A4 can be adjusted beyond the defaults though.
 

4745454b

Titan
Moderator
If you go back far enough, the CPU and the bus ran at the same speed. It was the 486 that first broke this rule going from memory. (or maybe I should say first consumer chip.) The bus is the pathway that runs from the CPU to the chips on the motherboard. The PCI bus ran at 33MBps, as did the system bus. The problem was they could get the CPU to go faster than that, but there was system instability if the PCI or system bus went faster. So the multiplier was introduced to allow the CPU to work faster. You now have the PCIe bus running at 100Mhz, while the CPU runs much faster than that. Depending on the CPU you are using you pick a setting higher then normal which is where overclocking (OCing) comes in. Every CPU I can think of these days allows for lower settings like you mentioned above. 22 might be the max, but you can run it slower than that without issue. That's how Intel/AMD does speedstep/cool n quiet.
 

Karadjgne

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Yep. Started out with the 386 SX-25, that was the base for the 486 SX-33, 486 SX-50. Intel introduced the DX later for a DX/2-66 and DX/2-100 which AMD bumped upto a DX/5-133. Those 2 chips formed the base for all modern systems running 200/266MBps pcie bus x 100.00 (BCLK multiplier) x multiplier on the cpu. The 200 base is rarely used because the ram is mostly 266 based. Only 3000MHz is 200 base, 3200MHz and 2933MHz are both 266 base, requiring a smaller multiplier than the 3000MHz, makes them more stable and easier for the memory controller.
 

Karadjgne

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Bios. But you have a dual core 1.5GHz cpu that has a max turbo speed of 2.2GHz and very specific cooling ability in a laptop. You most assuredly do Not want to go over 2.2GHz for any period of time as the cooling ability of the laptop will not handle the heat output.

Heat output does not scale linearly, in a straight line, it scales logarithmicaly. At max load and 2.2GHz you'd be looking at closer to high 80's. At 2.3GHz, add at least 5°C. At 2.4GHz add 10°C on top of that. At 2.5GHz add 15°C on top. Etc. At 2.5GHz you'd be somewhere around the 115-120°C point, well above thermal threshold and the cpu will be forced to throttle back to 1.5GHz just to stay cool enough to run, because of the increased voltage required to run the higher speed.

In a nutshell, it's a laptop, Stop messing with it.
 
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TheFlash1300

Great
Mar 15, 2022
242
4
85
0
Bios. But you have a dual core 1.5GHz cpu that has a max turbo speed of 2.2GHz and very specific cooling ability in a laptop. You most assuredly do Not want to go over 2.2GHz for any period of time as the cooling ability of the laptop will not handle the heat output.

Heat output does not scale linearly, in a straight line, it scales logarithmicaly. At max load and 2.2GHz you'd be looking at closer to high 80's. At 2.3GHz, add at least 5°C. At 2.4GHz add 10°C on top of that. At 2.5GHz add 15°C on top. Etc. At 2.5GHz you'd be somewhere around the 115-120°C point, well above thermal threshold and the cpu will be forced to throttle back to 1.5GHz just to stay cool enough to run, because of the increased voltage required to run the higher speed.

In a nutshell, it's a laptop, Stop messing with it.
Don't worry. Just tell me how to increase the multiplier. It's an experimental laptop, anyway...
 

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