Diferent memories in 1 system

6 replies [Last post]
ZeroCool_jf
Offline
Joined: 02/20/2010
Posts: 7

Hi, i recently got a Gskill 8gb 2x4gb ddr3 memory and it runs at 9-9-9-24 timing, but i also had on my system an almost identical memory, Gskill 4gb 2x2gb ddr3, but this one runs at 7-8-7-24 timing. since i needed more memory and didn't manage to find the same model anywhere i just got what was available. so i tried to set the memory to run at least 8-8-8-24 but it will crash, PLEASE note that i'm using all 4 sticks of memory now, so a total of 12gb of memory, so i had to leave my memory on BIOS set at 9-9-9-24, so my question is if my old memory is running at 9-9-9-24 or at its default 7-8-7-24 ? maybe anyway to get my old memory to run at a different timing ?

If any help here are the memory models

Old memory - F3-12800CL7D-4GBRM ( http://www.gskill.com/products.php?index=243 )
New memory - F3-12800CL9D-8GBRL ( http://www.gskill.com/products.php?index=239 )

Basically one is 7-8-7-24 with 1.6v and the other 9-9-9-24 with 1.5v

Also my system is running both memories at 1.8v as i got their frequency overclocked aswell.

Thx a lot for any help.

marijanovic
marijanovic's picture
Offline
Joined: 02/09/2011
Posts: 197

What is the point of overclocking your ram? You can't notice the performance increase, maybe just on memory benchmarks.

Set your timings manually to 9-9-9-24 with 1.6V and keep your memory as close to default frequencies as you can.

[center]My YT chanel | My PC | My Laptop | Mob: Samsung Galaxy Ace GT-S5830

Allen86
Offline
Joined: 07/08/2008
Posts: 163

So, I'm confused. Does it work? You make it sound like it works at a certain timing but when you try to lower the timings it crashes..

You should just find a spot your system is happy simply running the different types of RAM and just leave it there. ALOT of motherboards don't play nice with different RAMs put in at the same time. Like marijavonic says, you wont notice a performance difference really by overclocking your RAM.

Q6600 @ 2.4Ghz 4GB DDR2 800Mhz 500GB ATI HD 4850 512mb 22" LCD

ZeroCool_jf
Offline
Joined: 02/20/2010
Posts: 7

Thx for the advice's, but this is not exactly about the overclock, my memory are now set to run at 9-9-9-24, but 2 sticks there are a bit faster, they were made to run at 7-8-7-24, so i want to know if i can get that sticks to run at 7-8-7-24 and the other 2 at 9-9-9-24, so all the hardware would be in its default instead of just having 2 sticks at their default timing and the other 2 at a underclock. thx again.

btw my motherboard is good at overclocking, its a Asus Crosshair IV Formula, so i can tweak everything about my system.

marijanovic
marijanovic's picture
Offline
Joined: 02/09/2011
Posts: 197

You can't have different timings on different memory modules in the same system if that is what you ask.
Memory with lower timings works on higher timings with no problems, but hiher timings memory won't work on much lower timings than default.
But you can experiment, seting timings like 9-8-8-24 or 8-8-9-24 should work. But the voltage must be set to the voltage of the modules that require higer volatage or even a bit higher.
Again, you can not notice the difference between 7-8-7-24 and 9-9-9-24 ath the same memory clocks.
You could with DDR memory, but since DDR2 and DDR3 the RAM speed is not a bottleneck.

ZeroCool_jf
Offline
Joined: 02/20/2010
Posts: 7

Ok i understand, i tried 8-9-8-24 aswell but didn't work, crashed after a while, but maybe you guys can help me with one final doubt. why does my old memory has a max bandwidth of 10.7gb/s and my new memory has 12.8gb/s ? i thought they had the same speed with only a small difference in timing and they are running at the same timing eitherway.

i checked this info on AMD Overdrive.

here is a pic that might help. ( http://postimage.org/image/4fzozup7b/full/ )

eire1274
eire1274's picture
Offline
Joined: 09/12/2003
Posts: 1221

There are some memories that just simply WON'T WORK if you set them to run at timings lower than what they are rated for. In this case your slow module will not run properly outside of a 9 strobe CAS (column access strobe) timing. It needs that 9 strobe delay to sync the next module fetch, and pushing it will cause memory errors (and heat in the module) leading to crashing.

marijanovic is correct, run the system at 9-9-9-24 (the fast module will gladly back up to that speed) and you will be stable. The increase of running faster memory on DDR3 is negligible given the huge speed the memory bus now operates at.

CAS 7 vs CAS 9 on a 400Mhz (DDR) bus: a 27% increase in memory bandwidth
CAS 7 vs CAS 9 on a 800Mhz (DDR2) bus: a 9% increase in memory bandwidth
CAS 7 vs CAS 9 on a 1600Mhz (DDR3) bus: a 3% increase in memory bandwidth

Numbers are difficult to calculate (BIG NUMBERS if you want to be accurate) but that 27% increase in memory bandwidth resulted in a measly 1% increase in overall CPU arithmetic computational benchmarking (in other words, not noticeable to the user unless you are running LONG computations, as in a 50 minute long process could now be finished in 49 minutes and 30 seconds). That 3% is SO INSIGNIFICANT that it is simply NOT WORTH IT to push DDR3 rates unless you are calculating the string pre-universal physics of the Big Bang, in which case you will have your result in 999 years, 364 days, rather than in 1000 years.

The calculations are mind blowing in timing memories, because YOUR MEMORY CONTROLLER (e.g. your processor in most modern configs) also has a wait cycle in reading and writing, so where a DDR may be 9 cycles on the processor end, DDR3 can be as low as 1 or 2 cycle delays from the memory bus which is so close to the memory as to produce a difference that hardly exists.

http://en.wikipedia.org/wiki/Column_Access_Strobe
http://en.wikipedia.org/wiki/Memory_bandwidth

Added: forgot to mention, your memory bandwidth changed due to the slot timing, e.g. the top column next to "Freq". As the slot slows you are running a slower memory SPEED which will show a change in memory bandwidth. It appears that the faster of the modules is essentially slower because it drops it's operating frequencies to boost the CAS response. Obviously, 9-9-9-24 will be the most efficient behavior for your mixed equipment.

Nick McDermott - 3dGM Admin