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Gerbil In Training
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Joined: Thu Nov 26, 2020 7:03 pm

Which RAM Kit Should I Purchase?

Fri Nov 27, 2020 8:32 am

I was planning to purchase G. Skill RAM kit model F4-2666C19D-16GIS that has the following specs:
16GB (8x2)
SPD & tested voltage are both 1.2

However I can get the 3000MHz model (F4-3000C16D-16GISB) for the exact same price. Different specs:
Tested latency: 16-18-18-38
SPD speed: 2133MHz
SPD voltage: 1.2 (same)
Tested Voltage is 1.35

2666MHz is the highest I can go with my CPU, but since they are the same price I figured I'd go with the 3000MHz for some future proofing. E.g. if I upgrade my CPU in the future I can then take advantage of faster speed and better latency–was my thinking at first. Now however I'm concerned that since my CPU doesn't support the full capacity of the kit that I will only be able to use it's SPD specs which are worse than the 2666MHz kit. So I figured I'd ask here to see if that would be the case. I'd actually prefer the lower SPD voltage but I don't want to run at 2133MHZ, and I'm also concerned that the latency would be even worse than the 2666MHz kit.
Graphmaster Gerbil
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Joined: Tue Jan 17, 2006 6:56 am
Location: Big Rapids, Mich. (Est Time Zone)

Re: Which RAM Kit Should I Purchase?

Sat Nov 28, 2020 10:48 am

Which CPU and chipset do you have?

Bandwidth is slightly more important than latency. (CpU's have caches after all)

So faster MHZ is the more important consideration than timing.

So consideration should be mhz, cl, voltage, other timings.
Main machine: Core I7 -2600K @ 4.0Ghz / 16 gig ram / Radeon RX 580 8gb / 500gb toshiba ssd / 5tb hd
Old machine: Core 2 quad Q6600 @ 3ghz / 8 gig ram / Radeon 7870 / 240 gb PNY ssd / 1tb HD
Gerbil XP
Posts: 452
Joined: Tue Mar 30, 2010 11:27 pm
Location: Oklahoma

Re: Which RAM Kit Should I Purchase?

Mon Nov 30, 2020 7:50 pm

They actually go hand in hand. A 3600MHz CL15 set will have lower latency than a 3866 CL18 set. Start at about the 9:14 mark on this video for an explenation:

You also need to look at whether the DIMMs are dual ranked or single ranked. That can also have an impact on bandwidth. Here's another video (along with the comments) with more details, specifically around discoveries on the new Ryzen CPUs:
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