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Opinion on overclock settings

  • @GoldManSex778
    Sometimes I get low voltage, due to the wall outlet to usb being loose on either end. I didn't expect that this was the case but resituating the connection has usually 9/10 solved it.

    I think I have a 3M 20AWG no switch cord 5V 2.5A iTrunk media Power supply.

    I don't have much to say about the over_voltage settings and low-voltage warnings, I've tested multiple processes that use all cores, and I will get low-voltage whether default settings or no.

    sdram_over_voltage=5 needs to be over_voltage_sdram=5 I think I made the same mistake, it might have been posted incorrectly somewhere.

    You're welcome, I was learning a lot back then everything was new.

    I haven't refined the overclocking I was using last, this again is on a rpi3b+

    #dtparam=sd_overclock=100 #samsung sdcard

    If on a RPI3b+ over_voltage=; greater than 2 I think will have no use unless you are using arm_freq 600-1200. The AVS will typically raise the voltage to 1.3500V or 1.34375V if the arm_freq is above 1200 and will not go above 1.39375V. I have not been able to get a 1.4000V but I have gotten a 1.3850V ( I think it was an AVS 1.3350V + overvolt 2 (0.050V)).

    It is also possible to enter microvolt amounts for example:
    over_voltage=25000 is equal to over_voltage=1
    over_voltage=50000 is equal to over_voltage=2
    any microvolt amount entered will be emulated by the controller. This I think has no change on the AVS though, as that is something I haven't figured out yet entirely. If you have an AVS 143750 then adding over_voltage=6250 will result in 1.2V + 0.14375V(AVS) + 0.00625(overvolt) = 1.3500V. The AVS is set on boot it could be based on the last highest OSC of which is used to achieve the voltages or SoC core frequencies. I wouldn't recommend setting the osc manually using the config.txt unless you know what you're doing.

    The really high sdram_freq hasn't ever had a problem with emulations, however using memtester it still has errors. Lowering the arm_freq with this setting improves the stability lowering the errors found in memtester during bitflips, and the over_voltage_sdram_c can still be experimented with.

    I have been underclocking lately, unplugging the fan because it fits too tight in my case and gets pressed on by the heatsink. Probably invest in sandpaper soon.

    Here is a combined script for getting some useful data

    for id in core sdram_p sdram_i sdram_c ; do echo -e "$id:\t$(vcgencmd measure_volts $id)"; done
    for src in arm core h264 isp v3d; do echo -e "$src:\t$(vcgencmd measure_clock $src)"; done
    cpuTemp0=$(cat /sys/class/thermal/thermal_zone0/temp)
    cpuTempM=$(($cpuTemp2 % $cpuTemp1))
    echo CPU temp"="$cpuTemp1"."$cpuTempM"'C"
    echo GPU $(/opt/vc/bin/vcgencmd measure_temp)
    #free -h
    #df -h

    sudo chmod +x

  • @quicksilver Thank you, I am not surprised as I have heard of canakit's power supplies being subpar. Glad I have at least one good one, would you recommend the power supply you are using?

    As for the over-volting, the only reason I have it set that high is because I thought the under-volt warnings indicated that I needed to raise the voltages, but as you said, this didn't help.

    @Efriim thank you, that is a good point about the connection quality, the good power supply gives a satisfying snug fit feeling when I plug it in, the other doesn't. This could be compounded by the connector on the nespi.

    Thank you for reminding me about the over_voltage_sdram, I copied some of your settings a few times so it is possible. I remember you writing about that in a previous post and I made a mental note to check that.

    I don't understand what you mean by AVS (average voltage?) or OSC. I definitely will be bringing the settings down, although all the 5s really tickle my inner math teacher.

    Those are definitely some interesting settings you have and that script looks very useful!

    Thank you both again!

  • @GoldManSex778
    AVS is Adaptive Voltage Scaling, and OSC is I think Oscillator; something crystal.

    vcgencmd get_config int
    will tell you what is set for the config
    vcgencmd get_config int | egrep "(arm|core|gpu|sdram|osc)_freq|over_voltage"
    will highlight relevant freq and volt settings, the osc and avs_boost are in 0xF hex.
    the over_voltage_avs I don't think can be set in config.txt, however the desired osc can be set and again I would strongly forewarn against this.
    vcgencmd read_ring_osc 1 or 2, 8, 10, 11, 14
    will read other oscs. I don't know what all the different ones correlate to 1 - 14.

    with my settings I showed previously; increment to "over_voltage_sdram_c=5"; got no errors in 7 * 100mb tests, * 3 (edit: bad multiplication 3x interrupted at 7 was about 20) instances of memtester on 3 of 4 cores, just now. Now testing 4 instances of memtester on each core.
    I'm surprised I'm not getting undervoltage either.
    Test Completed
    4* memtester 100M 20 w/ 5 * ssh connections and EmulationStation in the background, taking commands from the 5th TTY.
    That is 400M of memory locked at one time and being processed by 4 cpu cores.
    I only encountered one error right after reading OSCs and issuing a few commands, yet it was the usual bitflip 154.
    This was excessive and a good test; Most applications never use all four cores. Next time I think I would run memtester 150 3.

    Micro-Usb connections are really obsolete, more so in this type of usage. A cool thing I noticed about the retroflag cases is; the microusb connector is on a separate board, a usb-c could be soldered on more easily.

    btw what model of pi are you using?

  • @Efriim Thank you! That looks like a lot of fun, maybe not as much fun as watching a bunch of dim-witted bots slug it out for hours. But most of the fun I now have on the pi is getting stuff like this working, ironic isn't it. Thank you for explaining that, I am able to follow most of what you have written, still my overclocking experience comes from the days when you had to flip dip switches or flash a bios to get a few extra frames in Half-Life; it astonishes me that I am over-clocking something by editing a text file.

    That is a very good idea about soldering another power connector, having a more robust power option would solve a lot of problems on the nespi case. I wouldn't be brave enough to try it with my soldering skills, usb-c would probably require a whole new board, the specs look scary 20v 5amps 100watts; electrical fires scare me, and these fly-by-night canakit power supplies do not ease my concerns.

    I am using a 3b+, NesPi+ case, 5v Noctua fan powered from the case, and a 256 gb flash drive stuffed in it; so there is no small load on it.

  • An honest question: Why are you using anything else than the official Raspberry Pi power supply? I see people complaining everywhere about sub-par power supplies, but the official one is dirt cheap and has never given me any undervoltage warnings. Not even when overclocking my Pi 3B+ and running Linpack on it.

  • @Brunnis That is a fair point, and for my part it boils down to caveat emptor. Even now when I look up "raspberry pi 3b+ power supply" on amazon, canakit dominates the top results with four and a half star ratings; below that is a galaxy of off-name brands, it is difficult for me to see where the official power supply is.

    The first power supply I got came with the kit, worked flawlessly. I went to local "cell phone accessory" stores but none of them had anything that went up to 2.5 amps. I have a drawer full of micro-usb power adapters, a couple of which go up to 2.4 amps but they don't push enough power for the 3b+. So when I ordered the second I went with canakit.

    I don't know whether I am a bad consumer who made poor choices, or a poor consumer given a choice between only bad choices.

  • @GoldManSex778 I can understand that. I tried searching Amazon and you're right, it doesn't seem like they even have the official one. Strange. It's easy to get hold of it here in Sweden.

    Just saw that CanaKit actually sell the official one:

    They only seem to carry the universal one. There's also another one that looks like this here in the EU:

    I have one of each and they both work equally well, as far as I can tell.

  • @Brunnis
    Likewise as GoldMan. I searched on amazon for the the PSU when I was upgrading around last christmas from a rpi2 that I had for a couple years and had found nothing of the official power supplies. I didn't know an official power supply existed until a couple months ago on the forums here, I almost denied its existence.

    I had increased the over_voltage from 1 to 2 on my configuration and I started to get undervolt warnings again. I guess the power of awareness makes this seem really obvious now, but I have quite a few things plugged in as it is sort of a balance of power. I set it back to over_voltage=1 and it is okay; over_voltage=1 has been enough for both core_freq=600 and arm_freq=1500 on rpi3b+.

  • @Efriim That is actually very reassuring, there is very little information that I have found that indicates what over-voltage "ought" to be sufficient. What all do you have connected to your pi, besides a commodore 64 printer?

  • @GoldManSex778
    Yes it is something to understand the needed voltage steps as well as the added AVS over voltage. From my note taking:
    The "over_voltage_avs=" will be used for arm frequencies in the range of 601-1200; the value assigned to over_voltage_avs is determined initially once at boot and is typically 31250(0.03125V) or 37500(0.0375V); giving the core voltage an amount equal to 1.23125V or 1.2375V respectively and any "over_voltage" is added on to those amounts, while "over_voltage_min" is added onto 1.2V until the AVS ignores it (possibly not exceeding 1.25V min).
    The "over_voltage_avs_boost=" will be used for arm frequencies in the range of 1201-1600; the value assigned to the avs_boost is determined initially once at boot and is typically 143750(0.14375V) 150000(0.15V); giving the core voltage an amount equal to 1.34375V or 1.35V.
    The determinants for the AVS values have been hard to comprehensively assign given their inconsistency with the other initialized config.txt settings; as for the assumed factor, it seems any of the arm and gpu core frequencies can have an effect, and further away from my understanding the OSC and PLL (phase locked loop) have a direct correlation.
    As well the implicit incorrectness in my notes, for example using an arm_freq less than 600 was away from where I wanted to test, and overclocking any of the gpu cores could have had more special results for the AVS not actually recorded.
    If the arm_freq is set to 1200 and the effective governor/scaler/forceturbo is actively using this mode, without over_voltage; the highest core/gpu_freq that can be used was around 530 at 1.2313V, this amount achieved graphical errors, the gpu doesn't like to get far past 500 while the gpu core doesn't go far beyond 600.
    Combining the settings below alone would result in halted system because the core_freq requires a greater voltage than the AVS provided by the arm at 1200, 1.2313V. There is perhaps an exception if exists a way to make effective the AVS_boost without the arm exceeding 1200, or just add a over_volt=5 and the additional 0.125V will be enough for core_freq=600, 1.3563V


    If the arm_freq is normally overclocked 1400-1500 then the AVS_Boost (~0.15V+1.2V) will be added (~1.3500V)
    The maximum core_freq was about on the mark of 608 with this voltage and 601 with the hinder avs_boost (1.3438V). These are maximums and I didn't prove any stability, only that core_freq=608 would not boot with less than 1.35V.
    The maximum arm_freq achieved with 1.35V was 1556 where an over_voltage of 1 was needed to go higher.
    I found that core_freq=600 is stable with over_voltage=0 and an avs_boost of 0x2191c (137500) + 1.2V = 1.3375V which is a lower voltage than I previously thought ( 1.34375V) by a 6250uV step.
    The AVS is weird.
    I guess it is worth noting that the AVS is dynamic across all cores, for example when a process uses all 4 cores it will use more voltage and give low-voltage warning in some scenarios. However I think the same AVS value will be shared regardless of the core.

    I have a Flash Drive and a Logitech Nano Receiver and... ethernet. If I plug in my controller to charge I get undervolt, If I then unplug the Logitech receiver then the undervolt warnings will go away.

  • I have this table I haven't updated it in a while the sdram voltages aren't really recommended.
    well none of it is really recommended, it is possibly difficult to read and get much useful information from.

    As it was initially stated by quicksilver, and I could confirm the other day experiencing this; the over_voltage in excess will contribute to the undervoltage detected across the board. Though it is possible and even practical to undervolt combining the use of "over_voltage_min" and setting the cores to lower frequencies.
    With only the setting arm_freq=1200. It was sufficient for all of the games I tried on psx and snes, while keeping a low enough temperature and voltage profile, not needing a fan or exceeding 1.2375V per core.

    Still remains, it is sometimes an imperfect power supply coupling or too many peripherals.

  • @Efriim said in Opinion on overclock settings:

    the highest core/gpu_freq that can be used was around 530 at 1.2313V, this amount achieved graphical errors, the gpu doesn't like to get far past 500 while the gpu core doesn't go far beyond 600.

    That makes sense, I was getting crashes in quake 3 when I would take the gpu/core up to 500 without any over-volting, it could have also been exacerbated by the power supply issue.

    Still remains, it is sometimes an imperfect power supply coupling or too many peripherals.

    Does that happen when you connect everything to the pi istelf? Looking at the megapi case (that a cool case!) It looks like it powers the usb hub the same way as the nespi case. I can't remember how the power is handled (whether it comes straight from the power supply or from the pi via the poor wiring). The case may be powering the peripherals in a first-pass manner causing the current to the pi to drop.

    I tested these settings for over 3 hours with no problems.


    over_voltage=1 is sufficient as you predicted, I probably don't need the the over_voltage_sdram either (BTW you were right, I had it miss-labeled as you did lol). It made a pretty good improvement, prboom now runs Doom at 3x resolution, even Ninja Baseball Batman runs smoother now, which surprised me.

    I tested arm_freq=1500 and got crashes on quake 3 after about an hour and a half, So I guess that is just a bit too high. Too bad, the 1500=500+500+500 would have satisfied my inner OCD.

  • @GoldManSex778

    Looking closely at the megapi board, the usb hubs appear to share a powered connection through the case as opposed to being more directly routed to the pi. Much too soon before, when I had been using over_voltage=1, having both my controller charging and the logitech receiver plugged in to these front ports did cause the power to drop low enough for warnings but not consistently leading me to think that it is the power supplies microusb connection.

    I have disabled the swap space on all of my installations, I can't say if this is very important because I haven't operated much at all while it was enabled.

    I'm wondering what make did your Pi come from? For example I have an element14 board.
    Also the microsd is it UHS-1 or 3 or a kingston class(4) or (6). A slower microsd in theory could offer instability when computations exceed its limits.

    I have $40 dollars that I have saved and want to spend on upgrading something on my pi.
    A controller is likely. I was also looking into getting an rtc module but these take the gpio that the case is already using, I don't know if I could fit it. An official powersupply was a maybe, but I'm finding I can work with the one I have now. A smaller fan that will fit correctly but sanding the case a millimeter I think will work just as well. There was a link someone shared me, that was a fan module controller that worked with retroflag cases, to control the fan power.
    Any other ideas? Controller recommends? What do you use?

  • @GoldManSex778
    over_voltage_sdram=1 can be discarded, as the default voltage for all the sdram components on the rpi3b+ are
    where over_voltage_sdram=1 will be ignored and 2 will step up the over_voltage_sdram_p by 1 giving all the value of 2.
    To lower the voltage below the default you have to use over_voltage_sdram_p_min=-1 and so forth.

    I found a Sega controller.
    Good reviews. I dont think I will be missing analog too much. 10ft usb.

    Some of the console controllers can be had for the same price, I think I saw an XB1 official for $22. Which has me hesitant on whether I should get something like this instead.

  • @Efriim I don’t know what make my pi is, i will note that here when I open this thing up again. SD card is a Sandisk ultra plus v10, it was $20 at Walmart.

    That is a pretty awesome looking controller, official sega! Do they make a Saturn version? That’s the only way it could be better. I use a ps4 controller through the Bluetooth, it has worked well for a year.

  • @GoldManSex778

    Sandisk ultra plus v10

    That is a class10, is equivalent by some standards to a UHS-1 by definition 10mb/s minimum transfer speed. This card has up to 48mb/s transfer. Which as far I know is high functioning and should be suitable for retropie.

    There are sometimes unique uses and advantages to having a class 1 or class 4, they have lower minimum transfer rates and so will have lower bus width(incorrect term?) when reading small amounts of data. Reading snes roms, saves and configs, will be more efficient however an entire operating system will be slow, as these also have lower top speeds, capacity and often quality.

    I've been testing the same settings 1500 and 500, 500, 500. It is possible that the manufacture of pi, has used different ram for the device. The brand distributors RS components; I have read they use a sdram chip of lower technical performance.
    Or it is possible that a reset was missed when changing settings.
    But don't be disheartened, the real performance is how you use it.
    Also I have only ever used and seen one rpi3b+ so I am skeptical that this is the case, but I am curious.

    There is a Saturn version of the controller, it lacks a "mode" button when compared to the genesis. I can't tell if I'm looking at computer generated imagery of the controller anymore when I look at amazon, I wonder how it feels and if it is the same size, if it makes my hands bleed, if the reviews are fake.
    I'm also considering the Super NES, PS2 or Wii Classic(nintendo) adapters to usb.

  • @Efriim I haven't had any problems with the sd card, roms are loaded from a usb drive anyway, so all it does is load scraped images and videos; the usb drive i use is USB 2.0 which has never seemed be an issue either. Loading times are satisfactory, even for large ps1 games.

    That sega controller would look dynamite with your case, but if the sky is the limit then why not consider a bliss box?

  • @GoldManSex778
    I only load dos/pdfs/ports/scummvm/savestates from usb. They were most convenient, since dosbox requires a configuration already, and scummvm creates a shortcut. The ports are easy to symlink and the savestates are like a backup. And they can all be plugged into a computer and used that way too.

    I have a UHS-3 microsd, I think it performs a little slower than a class-10 in regards to the entire operating system.

    Honestly you got to help me out.
    Playstation Classic or 8bitdo M30
    I get a controller either way, actually I get two if I grab a PS classic. The PS Classic controllers are only 5ft long.

  • @Efriim have you checked these out? I've found them to be pretty great for most systems on Retropie

  • @simpleethat
    I usually skip them when I see them for $50-$100. The dpad:analog integration is cool along with two more buttons, and it has wireless as well as a 10ft cord.

    I think I would get the MadCatz fighter style controller, MadCatz wasn't that bad back in the day. It loses wireless for a 9ft usb cable. And adds an analog and ps4 touchpad.

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