Phenom II C2 vs C3 Stepping.

[RyanGreener]

Hi everyone, I've read about these two and I'm just trying to get a clear decisive opinion on this. Is the overclocking difference that much on air (as opposed to water cooling/anything else extreme)? Or will they reach relatively same clock speeds? I'm thinking of buying a PII from someone on these forums, but I just found out it is C2 and did some research....

Any advice would be appreciated.

 

[Sp12]

It's there, but it's not super-significant. Average max clock is pretty close to ~4.2, but the C3 will do it with less voltage/heat.

 

[RyanGreener]

While we're on the subject, what's the typical safe vcore for PII's? I see that the safe 45nm limit is 1.4V, but I notice people just ramp up the voltage anyway. Can PII's handle high voltage better than most 45nm chips?

 

[Jovec]

While we're on the subject, what's the typical safe vcore for PII's? I see that the safe 45nm limit is 1.4V, but I notice people just ramp up the voltage anyway. Can PII's handle high voltage better than most 45nm chips?

I would say that most use 1.5v as the safe max voltage with proper cooling with Phenom 2s. 1.4v is stock/default volts for some P2s, and Thubans turbo at 1.475v.

 

[jtisgeek]

Not a big difference at all just depends on the chip if you go 1.5 and 4.0 need very good cooling remember amd doesn't go as hot as intel so 62c is the cut off really.

 

[RyanGreener]

I have very sufficient cooling, so cooling is not an issue. I just want to know the safe VCore to avoid any problems, as I plan on keeping my chip for awhile since it's a quad core

 

[DrMrLordX]

You really shouldn't go past 1.52v for everyday provided that your ambients are under control. You can try 1.55v and maybe get away with it, but your chip might degrade over time.

Also, stick to C3 chips if you're buying a Phenom II. Actually, unless you're getting a sweetheart of a deal, I'd say save your pennies and get an E0 chip (Thuban) if you plan on keeping the chip for awhile. Do this even if you don't need the extra two cores.

 

[RyanGreener]

You really shouldn't go past 1.52v for everyday provided that your ambients are under control. You can try 1.55v and maybe get away with it, but your chip might degrade over time.

Also, stick to C3 chips if you're buying a Phenom II. Actually, unless you're getting a sweetheart of a deal, I'd say save your pennies and get an E0 chip (Thuban) if you plan on keeping the chip for awhile. Do this even if you don't need the extra two cores.

I am getting the PII Quad Core C2 for 80 shipped, so to me, it's a steal. I'll stick to the best I can get at around 1.4V, then see if I'm happy from there. What are some good CPU-NB (North Bridge) voltages for it? I plan on getting some good NB Frequencies so I can get better performance. I hear most recommend 2400-2600 NB Frequency, which means 240-260 MHz "FSB"?

 

[StrangerGuy]

I am getting the PII Quad Core C2 for 80 shipped, so to me, it's a steal. I'll stick to the best I can get at around 1.4V, then see if I'm happy from there. What are some good CPU-NB (North Bridge) voltages for it? I plan on getting some good NB Frequencies so I can get better performance. I hear most recommend 2400-2600 NB Frequency, which means 240-260 MHz "FSB"?

There is no real need to OC the FSB with unlocked PIIs...You simply just crank up the multipiers for the core and NB.

 

[richierich1212]

C2s could reach about 3.7-3.8GHz with lots of voltage while C3s could hit 4GHz+ with about the same voltage. But since you're getting a C2 I wouldn't worry about it too much. Which processor are you getting?

 

[lopri]

Two outstanding differences come to mind:

1) C3 has hardware C1E, C2 doesn't.
2) C3 doesn't exhibit the weird "4GHz Barrier" under 64-bit OS.

I had 955BE C2 and C3, and C2 did 3.6 GHz at default vCore (1.35V) and C3 did 3.8 GHz at the same voltage. C2 required 1.40V for 3.8 GHz. No amount of voltage could take the C2 to 4.0 GHz to save the life. C3 did 4.0 GHz with 1.47 ~ 1.48V. (which is still a lot for 200 MHz increase) Given choice, I see no reason not to pick the C3 stepping Deneb over C2.

 

[DrMrLordX]

I am getting the PII Quad Core C2 for 80 shipped, so to me, it's a steal. I'll stick to the best I can get at around 1.4V, then see if I'm happy from there. What are some good CPU-NB (North Bridge) voltages for it? I plan on getting some good NB Frequencies so I can get better performance. I hear most recommend 2400-2600 NB Frequency, which means 240-260 MHz "FSB"?

I would recommend a CPU-NB voltage of 1.3-1.4v. Try to get away with as little as you can, obviously . . . also, as StrangerGuy indicated, try out some higher NB multipliers unless you really want to raise FSB.

 

[RyanGreener]

For the general public, I'm not "picking" C2 over C3...I just ran into a GREAT deal IMO. It's a Phenom II Quad Core 920, without unlocked multipliers. Also, I have an MSI 785GT-E63, and it doesn't seem to have the ability to mess with the North Bridge multiplier, unless maybe my processor isn't allowed to do it, which is why I plan on raising FSB instead of NB Multiplier (because it doesn't look like I can). I think I'll settle for slightly under 4.0 GHZ (like 3.9ish) as long as I don't need to ramp up the voltage and go nuts with it. My current, and very outdated CPU will not go over 3.4 GHZ no matter how much voltage I give it, so I'm hoping this Phenom will do me well

 

[busydude]

Sorry to rain on your parade, 3.9 Ghz for daily use on a Phenom II 920 is extremely rare and potentially unsafe. 3.6Ghz is a safe range for that chip.

Just to clarify, NB is located in CPU and not on the motherboard.

 

[RyanGreener]

Sorry to rain on your parade, 3.9 Ghz for daily use on a Phenom II 920 is extremely rare and potentially unsafe. 3.6Ghz is a safe range for that chip.

Just to clarify, NB is located in CPU and not on the motherboard.

3.6 GHZ isn't bad, considering it's got a lot of L3 cache and quad core. I wonder....will disabling one or two of the cores give me a better overclock? I know the arguments against this, but let's say I'm gaming in games that do not make use of the full quad core, will this theoretically give me a better OC?

Also, I know it's in the CPU and not the motherboard. I'm guessing this is in regards to my "raise FSB" comment?

EDIT: I went to AMD's website, and it seems that the max vcore for the Phenom II is actually 1.5V. I find that pretty awesome, as it's much higher than the "safe limit" for 45nm according to the sticky.

 

[richierich1212]

Yeah the Phenom II 920 & 940 were the very first Phenom IIs. I had a 920 and it couldn't really hit over 3.7GHz (was also probably my crap Biostar TA790GX A2+, or my lack of overclocking knowledge at the time.)

Then I had a 550BE that was able to hit 3.8 unlocked to quad, then got a 555BE unlocked that was able to go to 4.2GHz. And now I'm having fun with my 1055T. Can't wait for BD.

 

[RyanGreener]

Well when I get the chip and run into problems, I'll be sure to post ANOTHER topic

 

[DrMrLordX]

Your CPU should support CPU-NB multis as high as 10x, which is the default. You shouldn't need to adjust it as long as you leave your CPU multi at 14x, since 3.6 ghz will be around 257mhz HTT, so 2570 mhz NB. That should be attainable at 1.3v CPU-NB.

 

[Martimus]

EDIT: I went to AMD's website, and it seems that the max vcore for the Phenom II is actually 1.5V. I find that pretty awesome, as it's much higher than the "safe limit" for 45nm according to the sticky.

AMD and Intel use very different manufacturing processes for their CPU's. What is considered safe for one, is not necessarily safe for the other.

 

[RyanGreener]

AMD and Intel use very different manufacturing processes for their CPU's. What is considered safe for one, is not necessarily safe for the other.

Good to know.

 

[RyanGreener]

Your CPU should support CPU-NB multis as high as 10x, which is the default. You shouldn't need to adjust it as long as you leave your CPU multi at 14x, since 3.6 ghz will be around 257mhz HTT, so 2570 mhz NB. That should be attainable at 1.3v CPU-NB.

Quick question... the things I've read say that the processor has a default HT/NB of 1800 MHz. Shouldn't that mean the multiplier is 9, not 10?

 

[DrMrLordX]

That may be correct, in which case you might be able to get away with a lower CPU-NB at 257 mhz HTT. Running CPU-Z should clear that up for you (it will tell you what your CPU-NB clockspeed will be, and you can infer your NB multi from that).

 

[RyanGreener]

That may be correct, in which case you might be able to get away with a lower CPU-NB at 257 mhz HTT. Running CPU-Z should clear that up for you (it will tell you what your CPU-NB clockspeed will be, and you can infer your NB multi from that).

Ok thanks. I haven't gotten the CPU yet. It should be here in a day or two.