Help Me understand the FX-8300

[Juseh_]

Hello guys

I had a Phenom II 955 for 4 years and bought the FX 8300. I could hardly OC the 955, but is quite different with this one. Im not much an overclocker and im scared of 50+ degree temperatures.

Once i reach around 20minutes under load the average numbers remain almost unchanged.

I have the M5A78LMUSB3(4+1 phase, no heatsink) and i have a Hyper TX3(the old model) in the CPU. I wont explain now my airflow setup, but i TESTED a LOT and is the most balanced result i could get.

I have CPU overvoltage 1.30v in BIOS and 60% loadline calibration wich minimizes rollercoaster voltage, specially under load. CnQ, and Turbo disabled. C6 enabled.

I dont understand the low power, considering the +900Mhz. Also i have seen turbo applying around 1.40-1.50v to get 4.2ghz and i got there manually, all clocks perfectly stable at 1.28v

So, is the 8300 that flexible and not demanding? Did i get a specially good batch? or my board pretends that can manage but it's not?

 

[drea.drechsler]

I had a 6300 so my comments are mostly from my experience with that, but it should apply pretty well to the 8300 I'd imagine since they are the same early vishera silicon.

I could easily get mine overclocked to 4.4Ghz; I'd be pushing it at 4.5Ghz. But in my case it was mainly the VRM of my motherboard (M5A88M) that was the limit; 4.4 was the sweet spot that would P95 'til sunrise. But with no heatsinks so the FET's would overheat at 4.5 and start throttling in P95 small FFT's, even with a fan on them. Also, with only one LLC setting (enabled), I had to run Vcore at 1.45. That or the voltage fluctuation would take out cores until it cooled back down.

I was also running a TX3 which is not nearly enough even for a 6300: I wanted at least a Hyper 212 but it wouldn't fit my case. 4.2Ghz is just a baby step for these chips; you should consider 4.6-4.7Ghz a high-side target IF you have a mobo with a strong, high phase-count VRM and adequate cooling: I'd say a big Noctua for air or at least 240mm AIO for liquid.

With that setup my CPU temp was in the 55-60C range (only in Prime95) which I considered to be high although I understand, now, that people ran with temp up to just under the 70 degree shutdown limit and voltage as high as 1.55 bit-mining for months on end at 4.8-5Ghz range.

What I am interested in is what you OC'd your 955 to: i have one at 3.9G and am afraid to push it anymore. It's rock stable though, except that the darn FET's keep overheating and throttling the chip if I don't put a fan on them! My son has my 6300 now, overclocked to 4.4 again but at much lower voltage on a ga-990fxa-ud3.

EDIT update...just noticed! you have an M5a78 board. If i'm not mistaken it has the same VRM section as my M5a88. Maybe a better BIOS and VRM control, especially LLC, but that won't help enough: I can't see it holding an 8 core FX at 4.5 Gig in P95 small FFT's. It will throttle like heck. If you're serious about pushing the OC, you should seriously consider getting some Enzotech heatsinks to glue on the FET's:

https://www.amazon.com/Enzotech-Mosfet-Passive-Copper-10-pack/dp/B004CLDIHK

and then locating a fan to blow in that area. You're far closer to toasting a FET than the CPU when testing for P95 stability.

 

[Juseh_]

Considering your insight I have been running some more testing.I got rock solid stable voltage and clockspeed at 4.0ghz. Makes me think

I coul get the 955 to 3.4 and from time to time it would cause random unstable behavior or bootloops.Also it was reporting full TDP on full load, another reason i dont understand why im getting 60% with FX having normal temperatures (i touched VRMs, it hurts but doesnt destroy nor burn my finger)

 

[drea.drechsler]

Considering your insight I have been running some more testing.I got rock solid stable voltage and clockspeed at 4.0ghz. Makes me think

I coul get the 955 to 3.4 and from time to time it would cause random unstable behavior or bootloops.Also it was reporting full TDP on full load, another reason i dont understand why im getting 60% with FX having normal temperatures (i touched VRMs, it hurts but doesnt destroy nor burn my finger)

It could very well be your 8300 is throttling because APM is still enabled. In HWInfo follow the CPU Core Multiplier, if it drops from 21 (assuming a 200Mhz FSB at 4.2Ghz) to something MUCH lower in the middle of a P95 run then it's being throttled. Core Loading percentages probably won't drop at all as the cores are still working and loaded, just at a much lower frequency.

My M5a88 did not have a BIOS setting to disable APM on FX processors so it would throttle to stay within TDP envelope. If you can't find a BIOS setting in your M5a78 go googling for a DOS command line utility called 'AMD MSR Tweaker'. It may be all one word in a google search. It's a geeky command line utility but you can run it as admin in a Command Prompt and it will disable APM in FX processors. If you ever let the system go into sleep state it will wake up with APM enabled again.

With APM disabled it will then be the VRM that will start throttling the CPU LOL.

You can create a batch file and run it as a Startup job in Windows 10, just be sure to run as admin. But I did not run it all the time. Really only when I would encode a video would I need to run the batch file so it would stay working hard and get done quicker. Navigating windows, browsing the web while running Word/Excel -- even playing games rarely used close to 100% of even 1 core, much less substantially loading all 6 cores. One or two cores were always able to use all 4.4Ghz to quickly finish a thread before the processor even bumped the power stops enough to throttle.

Good luck