AMD FX processor family is positioned as overclocker products. All these processors have unlocked frequency multipliers, i.e. support simple overclocking. Note that Zambezi and Vishera both have sufficient frequency potential for a substantial performance boost, which, however, will be accompanied by serious increase in power consumption. Nevertheless, overclocking is an important competitive advantage of the FX series CPUs. Intel processors can only be overclocked as easily only if they fall into the $220+ price range. As for AMD, they favor overclockers on a budget, which is one of the reasons Socket AM3+ platform has become increasingly popular.
Speaking of the Piledriver microarchitecture, AMD stressed that it would have increased frequency potential. Therefore, we were pretty optimistic about Vishera processors being more interesting to overclock than their predecessors, which could only go as far as 4.6 GHz on average with air-cooling. However, right from the start it became clear that the new processors didn’t improve that much after all – the first FX-8350 processor we received in our lab overclocked only to 4.7 GHz.
However, it would be unfair to judge the overclocking potential of an entire family just by one single processor, so we decided to check out the overclockability of all four Vishera products. The goal wasn’t to set overclocking records, but to determine the frequency, at which new FX processors would be able to continuously operate in 24/7 mode without losing stability. Therefore, we set the processor Vcore at 1.55 V, according to recommendations from AMD engineers. The cooling system used was NZXT Havik 140. After that we tested our overclocked system stability by running OCCT 4.3.2 utility (30-minute test in Large Data Set mode).
First of all, we retested our FX-8350 processor once again. We hoped to get a better result than the original 4.7 GHz. However, we have already checked out a few other FX-8350 samples since then and none of them did any better. So, it looks like 4.7 GHz is indeed a typical overclocking maximum for a flagship AMD FX processor equipped with an air cooler.
Many of you may think that the junior processor models are manufactured using not the best semiconductor dies that is why their overclocking potential is usually much lower. In fact, this is a pretty rare occurrence, and our FX-8320 unit proved that. It easily hit the 4.6 GHz mark, which is only 100 MHz lower than the results obtained on its more expensive counterpart.
The six-core FX-6300, which features one disabled dual-core module, overclocked practically as well as the “complete” Vishera processors. It remained perfectly stable at the maximum frequency of 4.7 GHz.
We were very optimistic about AMD FX-4300 overclocking, because some sources reported success in reaching 5 GHz mark with these CPUs, however, we couldn’t verify their reports. Our particular processor with half the active cores and only half the L3 cache remained stable at Vishera’s typical max frequency of 4.6 GHz. At least without the gambling at potentially dangerous Vcore levels.
So, it looks like all FX processors on Piledriver microarchitecture, independent of the number of cores they have, can overclock to about the same level of 4.6-4.7 GHz with air-cooling. Yes, it is better than what we saw from the previous generation of AMD FX processors, but there is certain no qualitative improvement in their frequency potential as of yet. Nevertheless, overclockers should be pretty happy with these results, which are quite typical of 32 nm processors.
I would also like to mention that when we overclocked FX-6300 and FX-4300 processors by raising their Vcore to 1.5-1.55 V, they didn’t heat up too much at all. The temperature of our six-core CPU rose to 65°C maximum, while the quad-core temperature stayed at the ridiculously low 53°C. It means that you could raise the core voltage higher and achieve stability at even higher clock speeds. However, we cannot approve of this approach, because excessive increase in the processor Vcore may lead to die degradation and therefore this mode is unacceptable for long-term use.