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Some mainboard producers add a + to the specification of supported memory types (e.g. for ASRock X99 Extreme 3 supports DDR4-3000+). Does DDR4-3000+ somehow differ from DDR4-3000? The wikipedia article on DDR-SDRAM doesn't contain the sign+ or mention anything related. I don't see the difference reflected in selection filters in online stores.

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The "+" usually indicates that the motherboard supports RAM with a frequency of over 3000MHz. The OC in brackets means that the motherboard allows the RAM to be overclocked. The caveats being that you may need to increase the voltage and/or the timings in order to accommodate the higher frequency.

This article provides a good explanation on memory timings (e.g. 9-9-9-24):

Memory Timings/Latency Expalined

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    "The caveats being that a higher overclock/frequency will result in an increase in voltage and latency (in most cases)." The latency is measured in cycles(not time) for SDRAM, so the actual latency depends on latency number / the frequency you can reach. – rsaxvc Feb 14 '15 at 21:06
  • I didn't say it's measured in time. I simply stated that a greater overclock will have an adverse effect on latency. – Yass Feb 15 '15 at 1:38
  • That's just it, overclocking means you may need more latency cycles, but not actually more latency. 2 cycles at 100MHz is the same latency as 3 cycles at 150MHz. If you can run at 125MHz with only 2 latency cycles, the latency has decreased rather than increased. (Everything else in your answer I agree with and was helpful) – rsaxvc Feb 15 '15 at 18:33
  • So, are you saying I should change my answer to say latency cycles, instead of just latency? – Yass Feb 15 '15 at 19:24
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    I would just mention that you'll likely need to adjust the timings and/or voltages along with the new speeds. – rsaxvc Feb 15 '15 at 23:58

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