nover (overclocking) for CX II

→ **MyCalcs** profile · by **Khiemmy** » 24 Dec 2020, 01:47

So I've done some testing and here are my results:
Base freq: 444Mhz (x37)
Freq1: 222Mhz (/2)
Freq2: 222Mhz (/1)

Any higher and my calc freezes, requiring a reset.

My calc info:
ndless r2016
5.2.0.771
CX II CAS (N-0719AH)

→ **MyCalcs** profile · by **Khiemmy** » 24 Dec 2020, 09:12

For some reason, I cannot reach above 444Mhz without encountering any stability issues. So I have stuck to 432Mhz as even 444Mhz may work initially but would freeze my calc after a few minutes on gpsp. Anything above 444Mhz instantly freezes my calc, requiring a reset.

Could you please tell me how you reached 492MHz?

→ **MyCalcs** profile · by **Lionel Debroux** » 24 Dec 2020, 09:43

In general, the overclocking margin varies a lot from one device to the next, and previous Nspire models have shown a variable tolerance to overclocking as well, so I'm not too surprised that critor's calculator can reach 492 MHz while yours can't work in a stable way above 432 MHz.

→ **MyCalcs** profile · by **zephray** » 24 Dec 2020, 15:22

Currently we don't yet know how to control the memory frequency, so the memory is overclocked along with the processor. From PC overclocking experience, memories don't overclock well. You would be very lucky to be able to overclock the memory by over 25% without changing the timing parameter, which sets our current frequency limit at around 500MHz. I expect it to be able to overclock better once we gain control to the memory frequency or timing control.

Regarding the 432MHz issue, that seems a bit low. To find out if you are limited by the memory or processor, try overclock starting from 288MHz instead of 396MHz. 432MHz is 9% higher than 396MHz. If your calculator could run stable at higher than 288*1.09=314MHz starting from 288MHz, it means at 432MHz it is limited by the processor, as the memory could do over 9%. However if your calculator couldn't do over 314MHz, it means at 432MHz it is limited by the memory.

→ **MyCalcs** profile · by **Khiemmy** » 24 Dec 2020, 23:46

So I plugged my calc in which automatically set my clock speed to 288 MHz. I launched noverII and overclocked it to 322 MHz (closest clock speed) and it worked. Then I tried doing to it to 396MHz and it still worked. It was only when I
went above 444MHz from 288MHz when it started freezing my calc. So the overclocking could be limited by the processor or the memory could also be underclocked whenever it is plugged in.

Keep in mind that I have the non -T variant of the CX II. Maybe that makes a difference?

→ **MyCalcs** profile · by **zephray** » 25 Dec 2020, 05:50

Khiemmy wrote:So I plugged my calc in which automatically set my clock speed to 288 MHz. I launched noverII and overclocked it to 322 MHz (closest clock speed) and it worked. Then I tried doing to it to 396MHz and it still worked. It was only when I
went above 444MHz from 288MHz when it started freezing my calc. So the overclocking could be limited by the processor or the memory could also be underclocked whenever it is plugged in.

Keep in mind that I have the non -T variant of the CX II. Maybe that makes a difference?

Well it seems like I did something wrong when I initially tested it. For some reason my nspire had trouble reaching 396MHz when starting from 288MHz, so I suspected the memory timing issue. But now when I tested again, I got the same result as you do. So I must have done something rather stupid back then. Just ignore what I said in the previous post. It seems like adjusting the multiplier itself is sufficient for overclocking for now.

As a conclusion (at this moment), yes unfortunately it sounds like your nspire is only able to reach 432MHz.