geoffrey Posted July 31, 2013 Posted July 31, 2013 nice guide M I've been testing Arch Linux with Java 8 preview, no real gains there. Closing some processes might help you a little bit, but 'ps aux' (linux task manager) doesn't show any process that is taking a lot of cpu time Quote
Dreadlockyx Posted August 1, 2013 Posted August 1, 2013 We could use things like http://www.dhgate.com/product/lm317-assembly-board-dc-dc-ac-dc-voltage/159646661.html to control the Vin. Quote
Massman Posted August 2, 2013 Author Posted August 2, 2013 From what I see, the Vin doesn't affect the final Varm. I see my Vin dropping to 4.7V now, but the Varm still measures 1.4V. Seems like the Varm voltage will be fixed regardless of what the Vin is. I also read on the official RPi forums that the limit of 1.4V is hardware related, not firmware. Quote
Bobnova Posted August 2, 2013 Posted August 2, 2013 (edited) I think I found the external bits of the internal VRM. If I did, it's EPower time. First thing though is getting an install on there that will actually overclock. I'll post a few pictures in a bit here, need to take 'em and do some classy MSPaint work. EDIT: Here we go: Your mileage may vary, void where prohibited by law, not responsible for bad descisions, etc. I have a hell of a time making SD cards, so it may be a bit till I can test this. Putting some appropriate voltage caps across those two MLC jobs may well help, there's about 10mV of switching ripple on the VARM line, plus any transient ripple at higher loads. This is all at idle (no display attached, no Ethernet attached, booting to a command prompt I'd assume.), load ripple will be higher. Of course, more caps may blow things to hell, who knows. If you do and it is Varm and you make WRs, if you could credit me that'd be great Edited August 2, 2013 by Bobnova Quote
geoffrey Posted August 2, 2013 Posted August 2, 2013 (edited) you can find some schematics of the board online. I was just looking at them to notice that one possibility is indeed to do the same thing as mentioned above: Remove L5 and connect some external source to the point where you read the core voltage. Maybe L5 can stay in place and you just connect some external source to the voltage readout point, but it would not be the proper way of doing things. Don't know how things have changed or got better the last few years in overclocking The only thing that bothers me is the voltage feedback which could be monitoring the output voltage for low and high overvoltage. I need my Raspberry for programming stuff so I won't be testing it anyway Edited August 2, 2013 by geoffrey Quote
Bobnova Posted August 3, 2013 Posted August 3, 2013 Grabbed some time to redo the Raspbian(or whatever it is) install in the hopes that OCing will work. If it does it's external VRM time. I'm torn between something simple like a heavily heatsinked adjustable linear regulator (it's only 3.5w stock max draw for the whole board, that's not bad linear reg wise) or going whole hog and EPowering it. The linear reg would be nice from the standpoint of starting up along with the board for proper(ish) timing, but the EPower is just so much more me. It all depends on whether the damn thing will OC. If it won't OC adding voltage isn't exactly useful. Pi was free, if it dies I'll be annoyed, but I don't use it much. Maybe I can get a sample from someone to replace it if I give 'em some press. Quote
Massman Posted August 3, 2013 Author Posted August 3, 2013 You're correct on the read points. This is what I meaured (tested with changing the voltages) Quote
geoffrey Posted August 3, 2013 Posted August 3, 2013 http://www.raspberrypi.org/wp-content/uploads/2012/10/Raspberry-Pi-R2.0-Schematics-Issue2.2_027.pdf it has the caps/resistors/... mentioned in the schematic, so easy to find the correct spot on the pcb Quote
Christian Ney Posted August 13, 2013 Posted August 13, 2013 http://www.decryptedtech.com/news/element14-website-for-raspberry-pi-enthusiasts Quote
GENiEBEN Posted August 18, 2013 Posted August 18, 2013 (edited) Hey Pieter, in $ sudo apt-get remove openjre-7-jdk it should say openjdk-7-jre (or 6) OR sudo apt-get purge openjdk* Btw, I see there is a new build b102, here's the donwload link for ARM http://www.java.net/download/jdk8/archive/b102/binaries/jdk-8-ea-b102-linux-arm-vfp-hflt-07_aug_2013.tar.gz Changelog: http://download.java.net/jdk8/changes/jdk8-b102.html?q=download/jdk8/changes/jdk8-b102.html Edited August 18, 2013 by GENiEBEN Quote
geoffrey Posted August 22, 2013 Posted August 22, 2013 I tried the hardware modification with a linear voltage regulator but with no help. It does work, but I could not get higher clocks on the pi, in contrary my SD cards got corrupted as soon as I tried +1200MHz... L5 is back where it belongs now, I'm done with overclocking the pi Quote
geoffrey Posted August 25, 2013 Posted August 25, 2013 no pics, didn't draw any schematics but the mod is explained on the previous page I think: remove L5 on the downside of the board, take a variable linear voltage regulator, feed it from another USB post, hook up both (Vregulator and R-pi) GND lines and attach the regulators Vout to the Raspberry-pi Vcore readout point. Linear is not the best choice though, even with this low current dev-board I notice a lot of voltage swings between idle and load. Quote
Massman Posted August 26, 2013 Author Posted August 26, 2013 The swings might have been the cause of the SD-Card corruption. No voltage scaling doesn't make sense. Maybe you were just limited by the instable voltages? Quote
geoffrey Posted August 26, 2013 Posted August 26, 2013 nah, swings are really typical for linear voltage regulators Quote
Hiwa Posted September 2, 2013 Posted September 2, 2013 Interesting ... I go with the competition, looks funny Quote
rsnubje Posted February 11, 2014 Posted February 11, 2014 (edited) This got me about 40 MHz more on the core @ 1.4v and also about 40-50ish on the memory. The actual temp was around -24 according to temp gun and raspbian:P It's just a stock prometia btw. I think I need to do some modding on the raspberry. Let's say I use E-Power, I just remove L5 and connect E-Power to the V readout and a ground? Edited February 11, 2014 by rsnubje Quote
rsnubje Posted February 14, 2014 Posted February 14, 2014 Another friday with the Raspberry Pi This time: E-Power! This got me to about 1450MHz with around 1.8v real(DMM). Next time I will make it cold to go even further. For now just a score with 1400MHz. http://hwbot.org/submission/2500624_ Quote
rsnubje Posted February 16, 2014 Posted February 16, 2014 It's exactly like they said in this topic. Remove L5 and put power from Epower on Varm readout and I used the other side of the resistor as ground. Quote
teurorist Posted February 16, 2014 Posted February 16, 2014 is there any known cold bug ? ln2 ? Quote
rsnubje Posted February 16, 2014 Posted February 16, 2014 No problems till -24 Should try it on my cascade soon. Quote
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