Overclocking with hotfix 7alpha3


TitanUranus

Member
Joined
Oct 6, 2009
Messages
756
Location
UK
I'm not entirely sure if I'm putting this in the right place, so if any mod wants to move it please feel free.


Well, for the first time since Hotfix 5 I decided to do some extensive overclocking testing and I've gotten some surprising results. I'd like to know if anyone else experiences similar changes in their clocking abilities on their pandoras, or if they'd like to report anything related to this (either the emulator I used to test or the actual opp voltages). I'm not really asking for support, but some explanation would be very welcome. I used hotfix 7a3 running from SDHC in these tests. First off, even with reduced overclocking there seems to be a big improvement in the speed and functionality of a lot of software, especially the XFCE interface so this isn't a complaint or worrying me, it's just curious.


First off, I'll tell you what I was testing. I tested the maximum stable MHz for OPP1 through OPP5, and for a fair test I used PSXreARMed r13, playing 007-Racing through level 1 and loading and starting level 2. It invariably crashed when the helicopter in level appears or between loading levels if the clock rate is too high. Most often it'd just exit the emulator, but a few times I got a proper machine freeze crash and had to reboot. I chose the PSX emulator since it uses NEON and is unstable at previously acceptable OC values. Or so I thought.


OPP1 was a big surprise. On hotfix 5 and 6 I used the same settings I'd created under hotfix 5. The OS used to crash around 480 MHz on opp1, certainly if you loaded up any CPU intensive software. Now it (the OS) runs flawlessly and is stable (and remarkably playable) with the PSX emu right up to 525 MHz (but crashing at 530)! OC'ing with opp2 was similar, but less dramatic, with the OS and PSX running flawlessly at 660 MHz and crashing at 665 MHz. So there I was, thinking OC'ing would probably be better and more stable for other opp values too. Not so. I used to have everything running great on opp3 right up to 850 MHz, now the PSX emulator flakes out at a mere 830 MHz. At one point I had the OS running well at 875 MHz on opp3, but took it down to 850 on hotfix 6 when PSX started using NEON. So why the drop in stability at 850 MHz on opp3 between hotfix 6 and 7? It gets worse though, opp4 flakes out at 895 MHz and it used to be stable right up to 950+. What shocked me most is that opp5 became unstable at a mere 985 MHz when I regularly tested stuff at 1024 MHz in the past without any problems.


Perhaps the PSX emu just becomes unstable when overclocked beyond a certain point, I had the frame rate limiter off and the car was flying along at about double the normal speed, so could it be that this just causes the emu to freak out even without overtaxing the CPU? This may make sense as the OS seems stable enough at higher MHz when running lots of CPU intensive stuff like firefox 9 with flash sites. Or has the clockspeed come down because the voltages to the CPU were affected by the increase in voltage to the SD cards - in which case running from SD might be less stable than from NAND??? Does running from SD cause more heat that affects the max CPU MHz (and could this explain why OC'ing higher at opp1 was better as the CPU just doesnt get heat problems at low voltage?). Does anyone know any of these answers, and more to the point does anyone care?


I'm now astoundingly good at level 1 of 007-racing, and astoundingly bored of it too. Someone else might like to test their pandora using some other game/emu (N64 uses NEON too) with the same OCD style dedication with which I tested mine. Let me and the world know your results please.
 

Prometheus

Well-Known Member
Joined
Mar 8, 2008
Messages
9,475
This seems to fit more in General Talk, so if you don't mind, I've moved it to there. (Or here, rather. :p )
 

MrChops

Member
Joined
Sep 2, 2010
Messages
207
Did you test with neon on hf5 and 6? Or without in 7a3? Seems like a neon thing, I think I remember someone saying NOT to overclock with the new psx gpu because of it using neon.


If this is true, it begs the question: can we oc the neon independently of the cpu?
 

notaz

Certified Guru
Joined
Aug 23, 2005
Messages
4,913
Location
Lithuania
Website
notaz.gp2x.de
So were you testing r13 on both HF6 and HF7, or were your HF6 tests done on earlier version of rearmed? Since r12 amount of NEON instructions executed during emulation increased maybe 5 times or so because of the new GPU, also color conversion loop started using preloads that puts more load on CPU. More efficient software means more work for the CPU, it doesn't sit stalled as much as it used to because software can now give it more work over the same time period, causing it to heat more.


And no you can't overclock NEON separately, I think it's only possible to disable NEON unit completely to save power.
 

milkshake

Advanced Member
Joined
May 18, 2009
Messages
3,735
Age
36
Location
Rotherham, UK
basically testing your OC ability with PCSX reARMED was not the best idea try something else as we now know the neon code in the PSX emulator causes the system to be unstable if overclocked.
 

TitanUranus

Member
Joined
Oct 6, 2009
Messages
756
Location
UK
How terribly inconvenient all the other software is so piss poor at efficienct use of the CPU! PSXRearmed is a masterpiece though I have to admit. I'm still confused as to why the pandora OS is working at 525 MHz on OPP1 when it crashed at anything >500 on hotfix 5.
 
Last edited by a moderator:

Grench

Forum Addict!
Joined
Oct 3, 2008
Messages
6,623
Do I understand that right that your Pandora won't run at 600Mhz on OPP 1 at all?
 

TitanUranus

Member
Joined
Oct 6, 2009
Messages
756
Location
UK
Well, I just tried opp1 at 600 MHz and my pandora exploded in a shower of sparks and acrid smoke. Actually, it just locked up when I tried to launch Firefox, but I felt a certain dramatic flourish would make this reply more exciting. You mean to say your pandora can run at 600 MHz at opp1 (2 settings below the default opp3)? I thought running at 505 MHz while undervolted to opp1 was prety damn fine going!


This does beg another question, and one which a sage guru (as in wise, not as in sage the herb for sausage stuffing) like Notaz could no doubt easily offer an answer! Is it possible to change the oppX MHz for PSXrearmed alone? Since everything else on the pandora happily runs stable at higher clock rates and lower opp rates, I'd be sad to have to change the systems settings to increase voltage simply for the one emulator - even though it is worthwhile. Actually this isn't a massive problem, as I'm aware of the voltage switching values as I put them in myself. I can just set the clock speed of each game to an appropriate value (ie deliberately higher clock speed to the minimum MHz to kick in a voltage increase. As a general rule, I think running PSXRearmed at opp2 and 600 MHz is flawless anyway, it'd be nice to make a specific setting for it to crank up to opp3 beyond 600MHz for those times I want to enable the filtering though.
 

notaz

Certified Guru
Joined
Aug 23, 2005
Messages
4,913
Location
Lithuania
Website
notaz.gp2x.de
What filtering do you have in mind? The one offered in rearmed is done in hardware and uses no CPU.


I sure hope there will be more NEON-heavy programs with time. In fact, something like mplayer/panplayer might also show this if you feed it higher resulution video, as it has good amount of NEON in it.
 

TitanUranus

Member
Joined
Oct 6, 2009
Messages
756
Location
UK
That's good news about other progs using more NEON. As for the PSX if I turn on the default_up filter (smooths the picture edges) playing a game like "007 - Racing" starts to slow down massively. It works fine if you increase clock rate from 600 MHz to 810 MHz though, anything lower and it coughs and.
 

sukhi2011

Member
Joined
Apr 26, 2011
Messages
845
Age
43
Location
Birmingham
level Opp 3 is 800mhz but it can go just about 850mhz.


Psx shouldn't be overclocked more than 700mhz that's max,you are forcing it to run games more than 700 which isn't right,it will crash 100%.


Psx can run some games from 200-500mhz perfectly,why bother go higher than 500mhz,if it doesn't run at 500 then the best bet is just go between 600-700mhz only.


N64 runs most games at 250mhz full speed,sometimes 300mhz is even better,i use to clock to 1000mhz but seems it was same as clocking as 250mhz,only one game needed to clock to 1000mhz called deadly arts,rest of them run fine.
 

gotwake424

Member
Joined
Apr 2, 2011
Messages
380
Mine runs wireshark and firefox fine at OPP5 @1100 and higher and it crashes when set


its a little glitchy at 1100 works for about 20-30 minutes before freezing. Good 30 minutes tho ;)
 

TitanUranus

Member
Joined
Oct 6, 2009
Messages
756
Location
UK
N64 runs most games at 250mhz full speed,sometimes 300mhz is even better,i use to clock to 1000mhz but seems it was same as clocking as 250mhz,only one game needed to clock to 1000mhz called deadly arts,rest of them run fine.

Please tell me how you set N64 emu up, which version you are using an if possible attach a config file or 2 for me. I'd love to see N64 working at a decent speed but never got it right.
 

WizardStan

Mega GP Mania
Joined
May 24, 2008
Messages
16,733
Ocean says a lot of things, some of which are grounded in reality. It isn't always wise to take him at his word.
 

TitanUranus

Member
Joined
Oct 6, 2009
Messages
756
Location
UK
Ocean says a lot of things, some of which are grounded in reality. It isn't always wise to take him at his word.
Reminds me of when I was a kid and got all excited about those lovely c64 "ocean" movie tie in games.. they turned out to be full of shit most of the time!
 
Top