Performance of my expanded A1200 changes depending on the time of day...

[paul2004v]

So it's something I'd noticed years ago but I finally got around to taking a semi-scientific approach to the problem and logging the performance of my A1200 at different times of day.

The spec of the machine is as follows:

UK Commodore Amiga 1200 with KS 3.1
Phase 5 Blizzard 1230 IV with FPU + SCSI Kit and 2 x 64MB EDO SIMMs
1 x 2GB CF card

Over three days the averaged out results for the three test times using SysInfo 3.23 are as follows:

9am: 9.01 MIPS

3pm: 8.81 MIPS

9pm: 9.90 MIPS

Now clearly, this is a massive amount of performance to be gained or lost depending on the time of day that the machine is on and I can't for the life of me explain why the performance would vary so much over a 24hr period.

The only thing I can think of is that the Amiga is sensitive to power supply/demand variations and the resulting frequency variations in the supply but I'm thinking that I'm possibly mad to even contemplate this. SysInfo always reports the clock speed as 51.8 MHz

On the other hand, I'm still using the original PSU that shipped with the A1200 and it's marked as an A600 PSU so is probably underpowered a tad for the hardware it's powering and thereby sensitive to power supply variations...

Thoughts?

Paul

[DDNI]

It has nocturnal circadian rhythms

[paul2004v]

Originally Posted by DDNI

It has nocturnal circadian rhythms

Very nice I had to look that up.

Seriously though, I've been tracking the 60 min frequency change data on the National Grid website and testing and re-testing and there does appear to be a correlation between the mains frequency and the MIPS reported by SysInfo...

[Djay]

Originally Posted by paul2004v

Very nice I had to look that up.

Seriously though, I've been tracking the 60 min frequency change data on the National Grid website and testing and re-testing and there does appear to be a correlation between the mains frequency and the MIPS reported by SysInfo...

i did notice that i get a varied performance report, didnt think about the time of day being a factor... interesting!

i have a very similar set-up btw

[paul2004v]

Originally Posted by Djay

i did notice that i get a varied performance report, didnt think about the time of day being a factor... interesting!

i have a very similar set-up btw

I've been tracking it most of this evening and this is what I've found. There is a correlation between MIPS and power frequency but it is fixed at the point of startup so if you switch on the Amiga or reset it CTRL-A-A style at a low mains frequency point, you'll get less MIPS reported than if you reset at a point with high frequency delivery.

If you don't reset, regardless of the mains frequency, the MIPS will stay constant in relation to the frequency of mains at the point that the machine was last reset.

So to refine my findings, using the self updating data on the National Grid website.


Mains Frequency MIPS
@49.9 Hz @8.80
@50Hz @9.0
@50.1Hz or more @9.9

I really wouldn't have expected to see these results and I cannot explain why there's such a big jump in MIPS when the mains frequency change is only .1Hz from 50 to 50.1 but there you are.

I'd welcome others to try it out in the UK to see if they can re-create the same.

Paul