Question for undervolting gurus: 8350 or 8320 for 95w board?

[TRWOV]

Long story short:

1. The FX8300 isn't comerciallized over here.
2. The FX8300 costs the same as the 8350, considering the extra shipping (8320/8350 can be picked up locally)
3. The build requires a floppy
4. The machine is going to double as a WCG cruncher, hence the choice to go with the FX83xx
5. Given all the above criteria my only board choice is the Asrock 880GM-LE FX which supports the 8300 (95w TDP).

Basically I want to know if the 8350 requires a lower Vcore than the 8320 to operate at a certain frequency. As far as I can tell, the 8320 requires a higher Vcore to operate at 4Ghz than what the 8350 uses at stock settings. So, am I correct in my theory that using a 8350 and underclocking & undervolting it would work?

 

[vega22]

if i get your point.

yes the 8350 is the one you want as it is the better binned ic.

in that i mean it will oc higher on the same volts or give higher speeds from lower voltage.

or should in theory.

 

[cadaveca]

Long story short:

1. The FX8300 isn't comerciallized over here.
2. The FX8300 costs the same as the 8350, considering the extra shipping (8320/8350 can be picked up locally)
3. The build requires a floppy
4. The machine is going to double as a WCG cruncher, hence the choice to go with the FX83xx
5. Given all the above criteria my only board choice is the Asrock 880GM-LE FX which supports the 8300 (95w TDP).

Basically I want to know if the 8350 requires a lower Vcore than the 8320 to operate at a certain frequency. As far as I can tell, the 8320 requires a higher Vcore to operate at 4Ghz than what the 8350 uses at stock settings. So, am I correct in my theory that using a 8350 and underclocking & undervolting it would work?

Theorectally? Yes. With differences in silicon quality, however, you could get an awesome 8320, or a crap 8350.

 

[TRWOV]

Ok, will take the plunge and report back

 

[TRWOV]

Testing is underway

 

[TRWOV]

Update:

I put in an 8320 at the end since it was on sale (25% off). I left it at 3.4Ghz @ 1.25v (ACC ups that to 1.275 on load). I also disabled Turbo and CnQ (meaningless since it's going to crunch). There's no option to disable ACC though.

At stock volts, the board throttled it down to 1.4Ghz (same speed as CnQ). What I can make of this is that these FX CPUs are severely overvolted. With some more time I bet I could make it run at 3.6 or so (I managed to run it at 1.2v, 1.235v on load) but I preferred to up the voltage just to the point where it wouldn't throttle. Nevertheles, I'll make sure to buy some MOS-C1 heatsinks.


Why AMD puts such high Vcore? I suppose it has to do with the low common denominator. Maybe some CPUs do need these Vcore values to actually run but this 8320 sure is sweet

 

[vega22]

you also need to keep in mind that they spec them with a very wide range of other components in mind.

i mean it might need 100mv less than it states for stock speeds but when paired with a cheapo mobo and psu the vdrop and droop might take it to that level too.

 

[Bones]

Update:

I put in an 8320 at the end since it was on sale (25% off). I left it at 3.4Ghz @ 1.25v (ACC ups that to 1.275 on load). I also disabled Turbo and CnQ (meaningless since it's going to crunch). There's no option to disable ACC though.

At stock volts, the board throttled it down to 1.4Ghz (same speed as CnQ). What I can make of this is that these FX CPUs are severely overvolted. With some more time I bet I could make it run at 3.6 or so (I managed to run it at 1.2v, 1.235v on load) but I preferred to up the voltage just to the point where it wouldn't throttle. Nevertheles, I'll make sure to buy some MOS-C1 heatsinks.


Why AMD puts such high Vcore? I suppose it has to do with the low common denominator. Maybe some CPUs do need these Vcore values to actually run but this 8320 sure is sweet

You could probrably reach 3.5 stable with ease at the voltage you're using, FX chips are efficient with voltage and it shows from my testing. I also picked up an 8320 a little while back and it's been a pretty good clocker, only con is the obvious problem keeping it cool with all 8 cores running. I'm happy with my 8320 and it seems to be one of the good ones referred to earlier, clocks up well with not too much voltage used and can push my RAM fairly hard if I want. You won't be hitting these speeds with all 8 cores running without DICE or LN2 - I certainly didn't so disabled all but 2 cores for the run.

I can't complain about the results though esp from H2O cooling being used to do it.

Only other thing is the board you have might not want to support it fully as in it could be a touch unstable with the same settings compared to the likes of an Asus Sabertooth or even a CHV-Z since those boards clearly have the 8+2 phase to support these larger chips. BTW the above was done on a Sabertooth R2.0 board - I also have a CHV and a CHV-Z here.

 

[Lunat!c]

wtf windows xp...

 

[Bones]

wtf windows xp...

Yes, XP for benching Super PI, the preferred OS for that bench.
BTW this isn't a setup I use for anything else except benching. Using Win 7 as my everyday OS with XP serving as a benching only OS.

 

[Lunat!c]

oh ok