Personal computing discussed

Moderators: Flying Fox, Thresher

 
jmc2
Gerbil First Class
Topic Author
Posts: 160
Joined: Mon Aug 22, 2011 8:30 am

Ram speed vs tight timings?

Tue Nov 07, 2017 5:28 pm

---------------
Going to go ahead and buy my 16 core threadripper&GIGABYTE X399 Designare EX Motherboard
64 Gigs Ram during or after the black friday sales. Waited long enough or too long.
Ouch,Ram prices must have gone up $200 in 2 weeks. Was $600-700, now $800-900+
If there is any sale at all on the half doz. types of ram in the MB approved list
that I can find at Newegg or Amazon... best grab it while I can.
Prices only going up.
--------------

CORSAIR 16GB 2Rx8 CMK64GX4M4B3333C16 DS 16-18-18-36 1.35v V V V V 2133
3333 @ 16-18-18-36
vs
3000 @15-17-17-35
CORSAIR 16GB 2Rx8 CMD64GX4M4C3000C15 DS 15-17-17-35 1.35v V V V v 2133

I'm guessing that what is best would depend on exactly what you are doing (X264 compression)
and the exact program you are using?

Tho higher speed would help core to core communication.
Don't know if ram timings affect core to core or not. Speed does.
If ram timings do not affect the cores then I would go with the 3333 Ram

Thoughts welcome!
 
defaultluser
Gerbil
Posts: 15
Joined: Tue Feb 14, 2017 11:58 am

Re: Ram speed vs tight timings?

Tue Nov 07, 2017 6:53 pm

Timings usually mean very little in real-world performance. The speed is far more important.
 
just brew it!
Gold subscriber
Administrator
Posts: 49424
Joined: Tue Aug 20, 2002 10:51 pm
Location: Somewhere, having a beer

Re: Ram speed vs tight timings?

Tue Nov 07, 2017 7:27 pm

Having tight timings should only matter if the workload tends to perform lots of random small memory accesses, where latency matters more than raw bandwidth. Also keep in mind that timings are specified in clock cycles, so "looser" timings at a higher clock speed may actually be a wash: 24 cycles at DDR4-3200 speed is exactly the same latency (in absolute terms) as 20 cycles at DDR4-2666 speed.
Nostalgia isn't what it used to be.
 
jmc2
Gerbil First Class
Topic Author
Posts: 160
Joined: Mon Aug 22, 2011 8:30 am

Re: Ram speed vs tight timings?

Wed Nov 08, 2017 9:27 am

Ok, high speed ram it is!
Makes my choice easier if not cheaper.

Thank you.
 
dashbarron
Gerbil Team Leader
Posts: 288
Joined: Tue Aug 11, 2009 8:49 am

Re: Ram speed vs tight timings?

Wed Nov 15, 2017 8:14 am

just brew it! wrote:
Having tight timings should only matter if the workload tends to perform lots of random small memory accesses, where latency matters more than raw bandwidth. Also keep in mind that timings are specified in clock cycles, so "looser" timings at a higher clock speed may actually be a wash: 24 cycles at DDR4-3200 speed is exactly the same latency (in absolute terms) as 20 cycles at DDR4-2666 speed.


Hey JBI, want to piggyback off this thread. Where do you see the cycles on these sticks...?

I'm building a new rig, and looking at DDR4-3200~. There's a lot options, but something along the lines of G.Skills variant. I wanted to drop 16x2 sticks or 8x4,, but wasn't sure at what timing I should be aiming for, if it's going to make a really big difference. Seems like a few FPS at most in real world.

Examples being
    Timing 14-14-14-34 CAS Latency 14
    Timing 15-15-15-35 CAS Latency 15
    Timing 16-18-18-38 CAS Latency 16
 
spiritwalker2222
Gerbil XP
Posts: 454
Joined: Thu Dec 30, 2004 12:50 am
Location: Ottawa, Canada

Re: Ram speed vs tight timings?

Wed Nov 15, 2017 1:23 pm

jmc2 wrote:
---------------
CORSAIR 16GB 2Rx8 CMK64GX4M4B3333C16 DS 16-18-18-36 1.35v V V V V 2133
3333 @ 16-18-18-36
vs
3000 @15-17-17-35
CORSAIR 16GB 2Rx8 CMD64GX4M4C3000C15 DS 15-17-17-35 1.35v V V V v 2133


You know the faster ram (that you quoted above) has the tighter timings. 16/3333mhz = 4.8ns vs 15/3000mhz = 5.0ns

edit: The ram I've looked at typically all have the same absolute timings, regardless of speed. Included my old DDR ram.
Desktop: Skylake 6600K, GTX 660, Samsung 950 Pro, GA-Z170M-D3H
Garage mini PC: Kabylake 7100, X25-M g2, ASUS B250I, Antec ISK 110

Who is online

Users browsing this forum: No registered users and 1 guest