2013-10-06, 09:54
popcornmix I've done alot of testing on my Pi. Tweaking the OC settings. Some things I've learnt that never get mentioned and discussed I want to bring to your attention.
Mainly concerning the core_freq and the other GPU_freq
I've got a stable Pi running at
arm_freq=1115
core_freq=570
h264_freq=76
isp_freq=1
v3d_freq=76
current_limit_override=0x5A000020
sdram_freq=700
disable_pvt=1
over_voltage_sdram=8
over_voltage=8
hdmi_ignore_cec=1
initial_turbo=60
force_turbo=1
Yes thats h264_freq is 76. The reason being I'm running on a crt monitor that [email protected]. The Pi can still decode a 720p stream without frame drops and cast on my crt monitor. It can't do 1080p at this underclock. (I don't need it so thats why I've pritorised the limited power supplied to the Pi to better use)
The Isp controls the camera as you know but from my testing if left alone it always says its running @250 (default) when I use vcgencmd command. I learnt that setting anything under 70 sets it to 0 (using vcgencmd). Same is true for v3d/h264. But if you set it at 0 it defaults to 250. So I've set it to 1 and it stays at 0.
The h264 is self explanatory. Find the lowest value that the GPU can handle 1080p stream. I found it to be around 130 I think. I have'nt found the threashold for output of 1080p because I only have a crt monitor now. The v3d took me a while to figure out what was happening. I left v3d because I thought the Pi doesn't use it (at first I thought the Pi used it alot) but using an addon where their was writing scrolling along. My Pi always increased tempreture and kept increasing till I reached around 53 degrees c and then it frooze. So I learnt v3d (in xbmc) controls the moving elements and that on my monitor above 70 was good enough to run it.
The only other thing I noticed was that the lowest value any of the v3d/h264/isp can be are core_freq/7.5 if you have anything value less than that then they default to zero and taking v3d=0 you won't even get past the intial splash screen. Also by having such underclocked values for gpu_freq I was able to have a stable core value of 570.
I also learnt that the core has a maximum possible value of 600 (setting it past 600 defaults it to 500). (which is not mentioned anywhere else) I've gotten as far as 590 and it last under a minute but the difference in speed is dramatic from 570 to 590. And yes the tempreture is much lower at these values. And yes at these high overclock settings. my Pi freezes once it gets past 53 degrees.
I was thinking if you can find the threshold for output of 1080p then you can set that as your h264. also set v3d to be the same and have isp=1. Then the core can be set around 550. This will give speed improvments. What do you think?
If you want anymore information on my testing I'll be happy to answer your questions. I just thought I'll tell you my findings about the core and I can tell you first hand that it increases performance and reduces temp if you follow my priniciples
for anyone trying my settings you would need a good power supply. a USB install. Openelec and it will only work on crt but you can tweak to work on 1080p and also you would need a cooling method because if it gets past 53 it will freeze. I use about 20 small pieces of heatsinks.
Mainly concerning the core_freq and the other GPU_freq
I've got a stable Pi running at
arm_freq=1115
core_freq=570
h264_freq=76
isp_freq=1
v3d_freq=76
current_limit_override=0x5A000020
sdram_freq=700
disable_pvt=1
over_voltage_sdram=8
over_voltage=8
hdmi_ignore_cec=1
initial_turbo=60
force_turbo=1
Yes thats h264_freq is 76. The reason being I'm running on a crt monitor that [email protected]. The Pi can still decode a 720p stream without frame drops and cast on my crt monitor. It can't do 1080p at this underclock. (I don't need it so thats why I've pritorised the limited power supplied to the Pi to better use)
The Isp controls the camera as you know but from my testing if left alone it always says its running @250 (default) when I use vcgencmd command. I learnt that setting anything under 70 sets it to 0 (using vcgencmd). Same is true for v3d/h264. But if you set it at 0 it defaults to 250. So I've set it to 1 and it stays at 0.
The h264 is self explanatory. Find the lowest value that the GPU can handle 1080p stream. I found it to be around 130 I think. I have'nt found the threashold for output of 1080p because I only have a crt monitor now. The v3d took me a while to figure out what was happening. I left v3d because I thought the Pi doesn't use it (at first I thought the Pi used it alot) but using an addon where their was writing scrolling along. My Pi always increased tempreture and kept increasing till I reached around 53 degrees c and then it frooze. So I learnt v3d (in xbmc) controls the moving elements and that on my monitor above 70 was good enough to run it.
The only other thing I noticed was that the lowest value any of the v3d/h264/isp can be are core_freq/7.5 if you have anything value less than that then they default to zero and taking v3d=0 you won't even get past the intial splash screen. Also by having such underclocked values for gpu_freq I was able to have a stable core value of 570.
I also learnt that the core has a maximum possible value of 600 (setting it past 600 defaults it to 500). (which is not mentioned anywhere else) I've gotten as far as 590 and it last under a minute but the difference in speed is dramatic from 570 to 590. And yes the tempreture is much lower at these values. And yes at these high overclock settings. my Pi freezes once it gets past 53 degrees.
I was thinking if you can find the threshold for output of 1080p then you can set that as your h264. also set v3d to be the same and have isp=1. Then the core can be set around 550. This will give speed improvments. What do you think?
If you want anymore information on my testing I'll be happy to answer your questions. I just thought I'll tell you my findings about the core and I can tell you first hand that it increases performance and reduces temp if you follow my priniciples
for anyone trying my settings you would need a good power supply. a USB install. Openelec and it will only work on crt but you can tweak to work on 1080p and also you would need a cooling method because if it gets past 53 it will freeze. I use about 20 small pieces of heatsinks.
