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Overclocking discussion



  • @Riverstorm figured it was a little cleaner to continue our discussion here. What is you gpu_freq set to? My pi3 cannot get above 505mhz and be stable. I have noticed that the core_freq can be clocked a fair amount higher however and my current setting is 560mhz. This passed the quake 3 test for about 4 hours but I'm going to run it again overnight now that I know my cooling is enough for it.

    Quake 3 does run the CPU very hard too. I ssh into my pi and run "top" which shows your CPU and memory usage and quake 3 will regularly push my CPU to 100% usage.



  • Thanks Quicksilver I wanted to post this before heading out for the evening. I tested stable with the settings below using this link. It's been 100% solid except for Quake III crashed it within minutes. It froze but I still had access through Putty to reboot.

    I currently use a BIQU case with Shin-EtsuMicroSi thermal paste and run fairly cool under load around 56-57C.

    #CPU Overclock
    arm_freq=1260
    over_voltage=4
    
    #GPU Overclock
    gpu_freq=500
    v3d_freq=525
    
    #RAM Overclock
    over_voltage_sdram=6
    sdram_freq=575
    sdram_schmoo=0x02000020
    


  • @riverstorm you could try upping your over volt and see if that makes it more stable. If you have good cooling you can set a value up to 6 without voiding your warranty. Alternatively I would recommend turning v3d freq down as well. I know that the N64 optimization wiki says to set it at 525mhz but I doubt most Pi's are stable at that speed. You have to remember that v3d is a block (part) of the GPU. A pi 3 stock GPU speed is 300mhz so a jump to 525mhz is huge. Like I said my pi isnt stable when I set GPU to anything higher than 505mhz. Of course yours may be different but if quake 3 is crashing that tells me otherwise. Your best course of action would be to go back to a less aggressive overclock (or stock speed would be best) and test one change at a time.



  • Well I was working my backwards lowering my SDRAM frequency when I corrupted my SD card. Of course I didn't have it backed up. I was in the process of migrating all MAME ROMs into Arcade with a new image. It shouldn't take long to build up from scratch. Probably wiser to work with a dedicated card as I am sure it will get corrupted more than once working through this process.

    I am going to start with a stock image at defaults to make sure the Pi and SD Card are capable. I usually use SanDisk's Extreme PLUS cards. Q3 was fine with 1 bot but adding 8 is where it's quite taxing.

    Yeah 300 to 525 for the v3d is roughly a 57% increase I would imagine it's where Q3 spends a good amount of processing time/power as I believe v3d is a good bit about OpenGL, I think, not completely sure.

    I think I'll try upping the arm until it becomes unstable then bump over_voltage. If stable then continue upping the arm frequency. Then work through the SDRAM frequency and lastly the GPU.

    I am comfortable with bumping the voltage to 6 as the BIQU case seems solid. If not I have a 'negative space' case with the old school tall "spike" copper heatsinks with 10 or 12MM fan on top. They were great heatsinks but they don't seem to make them anymore. Mostly low profile aluminum now but I prefer copper.

    I am not sure the "Q3 level of stability" is needed outside of itself but it's a hobby and I think it will be interesting to see where the final numbers fall.



  • This post is deleted!


  • @riverstorm I am sorry to hear that your card got corrupted! That really sucks! I guess I have been lucky so far through all my testing.

    Personally what I do is set the over volt to 6 (since I know my cooling is more than adequate) that way I have potentially the most headroom for overclocking. Since I am interested in N64 emulation I really try to get the GPU as high as it can go and be perfectly stable. Once I get that maximum, I test by dropping the overvolt until it becomes unstable again, then I know where my over volt value needs to be set.

    Even though quake 3 probably works your pi harder than most things it still important to make sure that your overclock is 100% stable. You never know when something else that is very taxing on your pi will cause a crash with an unstable overclock. Some levels in some N64 games work the pi harder than others. Building from source as I understand it also works your pi pretty hard. Or there could always be updates to emmulators like mame, mupen64, reicast, drastic that work your pi just a little harder and suddenly your pi is crashing because your overclock is unstable. It just sucks that you found out the hard way what an unstable overclock can lead to. :(



  • @quicksilver said in Overclocking discussion:

    I am sorry to hear that your card got corrupted!

    Agreed, some good points on the proponent side. It's not a big deal really. I have the whole ROM directory structure, snaps, gamelist.xml, config files, etc. backed up to USB drive. It takes only an hour, maybe two counting all the waiting for the files to copy over. In addition I made some simple notes to supplement.

    @thelostsoul - What case do you use currently?



  • @riverstorm Strange, I changed my mind and deleted my posting and you still could read it. I will create a new topic, so it does not get off topic.



  • @thelostsoul if has to do with cooling or anything along those lines feel free to talk about it here.



  • I have two heatsinks, one on them on the cpu. They came with inbuilt tape and I just sticked them together. Maybe not the best idea, as there was probably no thermal paste on it and I have the problem that I can't get them off now. Do someone have an idea how to get them off, if needed? I fear that I could rip off the chip as well, while trying to remove the heatsink.

    Or would a fan be enough? Btw to answer the previous question, currently I am using a NES Case, which don't look like a NES. Its black and made by "The Perseids".



  • @thelostsoul oh yeah I think I was talking to you in the other thread. Like I said there, the thermal tape comes off very easy. Just gently wiggle and twist the heatsink until it comes off. Then clean any residue off with a little rubbing alcohol.



  • @thelostsoul said in Overclocking discussion:

    Do someone have an idea how to get them off, if needed?

    I would agree with Quicksilver. It's thermal tape and not thermal glue correct? I would get a solid grip on the board one side supported down your thumb and the other side with the other 4 fingers. Then gently rock it back and forth in different directions it will slowly start to loosen up. The tape has a bit of elasticity and you'll see it start to stretch a little as it loosens up.

    I had the same issue with the Flirc case and it took me about 10 minutes to break it loose but it will come loose without damaging the board with some patience

    Also I am not quite sure what you wrote above but I don't think you want to use thermal paste in conjunction with thermal tape. Either one or the other.

    Having a heatsink definitely helps but you can use a fan by itself and see if it cools sufficiently. Air has a pretty high resistance and heatsink helps tremendously moving heat off the chip.



  • I've been testing different cases lately too. I was doing some testing with thermal paste and tape with different cases in another post but it might do some good here. I just pasted them all together so if they don't make sense just let me know. The two cases I was mainly testing were the Flirc 2 and BIQU. Mentioning the Wicked Aluminum but that one is quite expensive but I hear great things about it.

    I've been testing the thermal paste vs tape we talked about a while ago on a Zero. They both seem to do well. I don't think paste is a clear knock out but maybe a preference and definitely an alternative if you don't have one or the other handy.

    It's fairly rock solid when cool but when heated up it's a bit slippery but seems to sit fine. It's easy to break the cohesion if bumped when cool which would be a CPU killer on a real PC or a degradation in cooling but doesn't seem to effect the Pi to much when heated back up.

    It can be a bit messy and a bit of trial and error getting the correct amount but it does work well. The tape I have been using is easy to pull off in a single piece. I've had some heatsinks where it is gooey and messy to remove though once the heatsink was removed. Inside a larger unit [arcade style unit] I would do paste but if it's a small case that's portable being shoved in a bag, pocket, etc. I would probably use tape.

    If I get some time I will sit down do more exact temp difference.

    I was a bit disappointed in the Flirc 2 case for cooling. Aesthetically it's my preference [for looks] but I just ordered a BIQU from what I read it cools better due to 3 points of contact [main SoC, Ethernet & memory] chips with a solid aluminum column vs. the Flirc which covers only the main chip and it's a hollow column not to mention the rubber top covers the hollow column [hole] which I would say holds in more heat.

    That nice looking "Wicked Aluminum" case I hear cools incredibly well with it's 3 chip contacts and paste. It's solid aluminum and screws together tightly so no slippage but when the BIQU is similar and about 6 times cheaper I'll give it a shot even if a few degrees warmer. Basically I am hoping to get rid of the fan and go all passive cooling overclocked.

    The original tape that comes with the Flirc is thick. It's cut smaller by quite a bit from fully fitting the main SoC, not sure why. So I tried cutting a proper size piece from stock I had but it's to thin to fill the gap between column and chip. I read Artic (not Artic Silver) makes a thermal tape of different thicknesses.

    The BIQU's columns are thinner/smaller than the on board chips so they only cover a portion of the chip (save some aluminum by the manufacturer) but it's solid aluminum. Also you can't use the case mounting holes on the back of the case as even low profile pan head screws would come in contact with the board and short out on the bottom. They cut one big hole to cover all ports instead of individual like the Flirc

    The Flirc has nice attention to detail cutting around each port. The two tone case and rubber top are nice looking and feel but not geared as well toward cooling. Plastic bottom with holes.

    The Wicked Aluminum did all things right the first time but at a ridiculous cost as the new B+ with an IHS (looks like it only covers the top of the SoC instead of enclosing it from the pics) almost makes it void now as I am sure the B+ will not even fit that case. The Flirc might be ok as the gap is fairly large and paste isn't even an option with the Flirc so the IHS might narrow it enough.

    I read it's beneficial to take the time to sand the contact points to remove the paint on the BIQU for bonus cooling points. Keeping it level is key like lapping a CPU. I should have it this weekend to mess around with. Well I ordered it Amazon Prime anyway as we keep a subscription but Prime hardly means anything anymore. It seems very select on what arrives in two days.

    Yes I've seen thermal compound "crust" when properly applied (thin enough) and screwed down after enough time but usually a few years. I think AS5 recommends around a certain number of cycles of heating and cooling to cure and maximize cooling.

    It does look like it would work but without it being clamped down in some fashion it seems like it would loosen up between cycles or seasons. I know here we have extreme dry in the winter to extreme humidity in the summer and that makes a big difference. The freezing temps in the winter cause "frost heaving" pushing up solid concrete, footings and building foundations can be moved unless you keep them below the frost line but most contractors in this type of climate know better. Probably not quite the same thing but doors are more snug in the summer when full of moisture and loose in the winter when dry, windows, furniture, etc. That humidity can expand or lack of can crack and dry things out pretty badly.

    The viscosity of compound changes when it's hot too making it more suspectable to moving. I did tin the SoC and just put a dab in the center. which misses the extreme corners if you look at the spread pattern. I remember going through that stage of applying and reapplying paste to a CPU to find the maximum cooling for your PC. You can get them (the corners) if you don't mind some excess squeezing out the sides but some of the metal based ones are electrically conductive and would require cleanup due to shorting. With some of the dual core CPUs Artic Silver recommends a thin line down the center but there's not enough room on the Pi. I dislike it when it squeezes out the sides and stains the motherboard CPU socket around the chip.

    A good "clamp" might gain you a few degrees. Either way I agree I think paste or a good quality tape are going to keep the cooling well within spec.

    Just to follow up on the BIQU case. It does cool much better than the Flirc 2.

    The columns are much slimmer than I thought from looking at pics. They also have "dimples" in the contact surface. Not sure what the reasoning is even though it's a molded case. Two dimples in the main SoC column and one in the ethernet(?) chip. The underside memory(?) chip had no dimples but the surface was convex and required sanding it down.

    The contact surface on the columns sanded easy revealing the metal. The underside chip took a bit more work as it was convex and also tight to work inside the lip of the case. The top columns are open and easy to work with. I used a fairly high grit sand paper as my brother does auto body but 300 grit or so from the hardware store works. I used a small block to keep the sanding level.

    I did a "cold press" with thermal paste and the columns hit near dead center. I used Shin-EtsuMicroSi vs AS5 as the viscosity is almost clay like-ish and it worked nicely to fill the dimples and set well.

    I was testing in an ambient of around 75F/24C. With the BIQU I leveled off around 56-57C. The Flirc 2 was around 74-75C. That's with all settings overclocked and a voltage bump.

    Another noticeable drawback of the BIQU case is no visible lights as they are completely enclosed inside the case.

    I like the BIQU as it cools easily in the 50s with no fans or extras. It's quiet and it's a decent case with a decent finish for around $12 US which is a good bit cheaper then the Flirc 2 even though I like the Flirc 2 look better.

    Something I found interesting or I didn't think about really. Is the when I removed the Pi from the Flirc it was "stuck" it took about 10 minutes of gentle prying around the edges of the board to get the tape to break loose. There's no easy way to pull them apart as the Pi is slightly coutersunk into the top.

    The other thing I noticed the tape was roughed up around the edges but smooth and flat in the center, basically untouched. I came to the conclusion that not all the SoC's are completely level so that chalks one up to paste being a better option in some scenarios. Plus with paste it [cases] comes apart much easier.



  • @riverstorm said in Overclocking discussion:

    I was testing in an ambient of around 75F/24C. With the BIQU I leveled off around 56-57C. The Flirc 2 was around 74-75C. That's with all settings overclocked and a voltage bump.

    Are those the temps at idle? Or while running a program? If so, which program. Im curious how your numbers stack up against my Kuma 9k case. Great info btw.



  • @quicksilver said in Overclocking discussion:

    Are those the temps at idle? Or while running a program? If so, which program. Im curious how your numbers stack up against my Kuma 9k case. Great info btw.

    They were running a game. More of a real world test. ;) I set the Governor to performance so it stayed pegged at 100% for 4 to about 6 hours. The game was Dungeons & Dragons: Shadow over Mystara (ROM=ddsomu.zip) in lr-mame2003 and also a sdbench script (it's pasted in a Wiki somewhere).

    If you have another test you like to benchmark with just let me know so it's more apples to apples that might be better. I hope to get a chance this weekend to do some overclock testing.

    What do you think of this guys script? It looks like a nice battery of tests here. I found it trying to find that sdbench stress test I used. It [sdbench] seems to focus more on reading/writing and memory than graphics though.

    What are you full overclock settings? I can't seem to find a link to the Kuma 9k when Googling. If it's passive and cools better I'll give it a whirl.



  • I would be curious to hear of any numbers used for the Pi3B+

    I was overclocking my Pi3B at about 1400 before but now that the baseline is 1400 with a B+ I would love to hear a suggestion for a stable overclock value for it.

    I have a flirc2 case for it. Had to shave the heat sink "paste" pad down to about 25% thickness to get the B+ to fit properly in the case.



  • @alturis said in Overclocking discussion:

    Had to shave the heat sink "paste" pad down to about 25% thickness to get the B+ to fit properly in the case.

    That's interesting mine fit without modification. There must be some variance in the manufacturing process or maybe they ship different thermal tape to what's on hand.



  • Yeah, actually the fit is still not exactly perfect. It's pressing down pretty tightly on it compared to how it is with my Pi3B causing an ever-so-subtle bend in the board.



  • @riverstorm https://www.amazon.com/SNES-inspired-Raspberry-Case-functioning/dp/B079T7RDLX

    Comes with a custom heatsink and thermal paste

    If you really want to test the cooling capabilities of a case, try running cpuburn-a53. This will test your cooling and if your power supply is adequate. If you can run it without throttling, your cooling is very good.



  • @alturis I have heard of people getting the 3b+ up past 1500mhz. The problem is that people claim all sorts of numbers with no proof of stability. For example my pi3 will boot at 1475mhz but is only stable at about 1350mhz. Anything past that and eventually I will get a crash if I run a particularly taxing emulator.


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