PSU and RAM question

[Bryan]

Huh, that's bizarre. So something doesn't work the same with X79 as it does with the regular i7 rigs then, because they advertise the motherboard going all the way up to DDR3 2400. Oh well. So what I want is DDR3 1600 with the lowest CAS numbers, right?

The MB supports up to DDR3 2400. However, look at page 2.-6 of the manual ... " Due to Intel CPU behavior DDR3 2200/2000/1800 MHz memory modules will run at DDR3 2133,1866/1600 as default."

It may be you can manually make them run at their real freq but if you select DDR3 1800 in BIOS it says it will run as 1600. Since the MB supports 2400 and that isn't shown on page 2-6 maybe that will run at speed.

You're better off watercooling and running the CPU at 4.5G like Al is doing. I doubt you can get away with air cooling at that freq. Then again, I never tried it

[John P. Myers]

Looks like it's rounding the RAM speed down to the closest multiple of 266MHz. That means 2400 should run at 2400, but the extra latency isn't worth it. Going beyond 1600MHz with DDR3 hasn't shown any improvement for the extra money.

DDR4 is a different story. 3200MHz is the sweet spot there right now.

[DrPop]

OK thanks, that clears that up. Any reason other than power savings to get the RAM at 1.5V over the 1.65V sticks? I honestly don't know what difference that makes other than using 0.15V less?

[John P. Myers]

1.5v is JEDEC spec. 1.65v is 10% above spec and just means you're paying extra for factory overclocked RAM. And it'll run much hotter. The best latencies are available in the standard 1.5v

[DrPop]

Thanks! Makes perfect sense, I appreciate it.