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.
asked Feb 14, 2015 at 13:12
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1 Answer
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):
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1"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.– rsaxvcFeb 14, 2015 at 21:06
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I didn't say it's measured in time. I simply stated that a greater overclock will have an adverse effect on latency.– YassFeb 15, 2015 at 1:38
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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)– rsaxvcFeb 15, 2015 at 18:33
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So, are you saying I should change my answer to say latency cycles, instead of just latency?– YassFeb 15, 2015 at 19:24
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1I would just mention that you'll likely need to adjust the timings and/or voltages along with the new speeds.– rsaxvcFeb 15, 2015 at 23:58