add arrow-down arrow-left arrow-right arrow-up authorcheckmark clipboard combo comment delete discord dots drag-handle dropdown-arrow errorfacebook history inbox instagram issuelink lock markup-bbcode markup-html markup-pcpp markup-cyclingbuilder markup-plain-text markup-reddit menu pin radio-button save search settings share star-empty star-full star-half switch successtag twitch twitter user warningwattage weight youtube

Help needed to find out if 3200 RAM is equal of faster than a 3600 with higher timing

mhweb
  • 5 months ago

I'm planning to upgrade the RAM on my AMD 2950X system, and I found two kits that are compatible. However, I'm trying to figure out which is better.

On one hand, I have an 128GB (8x16GB) 3200 kit with timing of 16-18-18-38 (F4-3200C16Q2-128GTZKW). On the other hand, I have an 128GB (8x16GB) 3600 kit with timing of 17-19-19-39 (F4-3600C17Q2128GTZKK).

I was thinking about getting the 3600 kit, but seeing the timings, I'm not so sure. I found online a formula to calculate the nanoseconds, and the 3200 kit pulls ahead with 5.0ns, while the 3600 has a 5.2ns delay. However, doesn't the 3600 means that work will done faster than the 3200?

In this case, is there any benefit between the 3600 over the 3200 kit which is $100 cheaper?

Thanks,

Comments

  • 5 months ago
  • 2 points

The 3600 kit is over all faster, but if money is a real consideration, I would try to get the most out of the 3200 kit as you possibly can

  • 5 months ago
  • 1 point

In this case, the money isn't an issue, I just want to make sure the extra $100 is worth the spending.

Thanks,

  • 5 months ago
  • 2 points

Real latency

F4-3600C17Q2128GTZKK / 17-19-19-39 = 9.44ns

F4-3200C16Q2-128GTZKW / 16-18-18-38 = 10ns

So theoretically, the 3600MHz kit will be the better option.

  • 5 months ago
  • 1 point

Out of curiosity, what formula did you use?

Thanks for the reply.

  • 5 months ago
  • 2 points

I use that formula.

[CAS / SPEED] x 2000

2000 because it's double data rate.

  • 5 months ago
  • 1 point

The timing specs are in clock ticks. One clock tick is 1/MHz microseconds or 1000/MHz nanoseconds. So for example the 3600 MT/s kit (there is no such thing as 3600 MHz memory, never mind what all the manufacturers incorrectly label it as) has a clock speed of 1800 MHz, because it's DDR (double data rate) memory. 1000/1800*17 works out to 9.444... ns.

  • 5 months ago
  • 1 point

If you're talking about CAS timing, the numbers are actually 10 ns for 3200CL16 and 9.4 ns for 3600CL17. Negligible difference. What might matter, a tiny bit, is that the CPU infinity fabric will run at 1800MHz with the 3600 MT/s memory and 1600 MHz with the 3200 kit. That's assuming that you can actually get the memory speed up to 3600 with all 8 sticks!

The performance difference in the end will depend on a) the speed you manage to attain with your particular CPU and motherboard, and b) the kind of work you're doing. It's going to be a small difference even best case, maybe a couple percentage points. If you aren't doing unusually memory-intensive work, you're probably better off going with 3200 and putting the $100 into your pocket.

  • 5 months ago
  • 1 point

Well, one of the reasons for the upgrade is that I work with a bunch of virtual machines at the same time and I need them to be responsive. I think this will be most intensive workload. Other than that, I'll be doing some video rendering and a lot of apps running at the same time.

Thanks for the reply.

  • 5 months ago
  • 1 point

Any reason when it wouldn't run at 3600 with all the 8 sticks? Thanks,

  • 5 months ago
  • 1 point

8 sticks loads down the memory controller. Ryzen 1st and 2nd gen had trouble with the rough equivalent (4 sticks into a dual channel controller). Whether that extends to Threadripper 2, I'm not sure; but it's definitely true that the more you load up the memory, the harder time the memory controller has. And, 3600 is pretty close to the top end of the Infinity fabric speeds anyway, so you're pushing the edge on both ends.

It might work at 3600, it might not. There's no way to know for sure without trying it with your particular CPU, motherboard, and memory sample.

  • 5 months ago
  • 1 point

Thanks for the reply. I decided to get the 3200 kit.

[comment deleted]

Sort

add arrow-down arrow-left arrow-right arrow-up authorcheckmark clipboard combo comment delete discord dots drag-handle dropdown-arrow errorfacebook history inbox instagram issuelink lock markup-bbcode markup-html markup-pcpp markup-cyclingbuilder markup-plain-text markup-reddit menu pin radio-button save search settings share star-empty star-full star-half switch successtag twitch twitter user warningwattage weight youtube