Windows 7: What is faster and better for an FX8120: 1866 CL10 or 1600 CL9?

I'm just finishing setting up a new build (will update specs when done).

ASUS M5A97 EVO
AMD FX 8120
4x Patriot Viper 3 8 GB 1600 9,9,9,24
ASUS HD7870 DC2, 2G DD5
2x Seagate Barracuda 1TB, 7200, 64 MB, RAID 0 (yeah, I know. Have very solid backup strategy though)
Kingston Hypex 3K 120 GB

I've over clocked CPU to 4300, 1.39V.
Every thing runs smooth and stable with memory at 1600, 1.6V, 9,9,9,24 T2.
When I try to increase speed to 1866, same voltage and timings, mobo only sees 16 GB out of the 32.
Same result if I try to tighten timings to 8,9,8,24 at 1600.
To get mobo to see all 4 sticks I need to either run them at 1600 9,9,9,24 or at 1866 10,11,10,27. Is this a mobo, CPU limitation, or is there something I could do to get mobo to see all memory at 1600 with tighter timings or at 1866 with CL9 timings? Increase voltage?



Anyhow, what is faster, 1600 9,9,9,24 or 1866 10,11,10 27?
Benching with SiSoft SANDRA I get 21 GB bandwith at 1866 and 19 GB at 1600, in both cases wit above stated timings.
In both cases latency is very poor, around 60 ns. Anything I could do to improve latency?

Also, I read in several places that AMD FX CPUs work better with tighter timed memory that higher speed memory, i.e. 1600 CL9 vs 1866 CL10. Is this so?

Any advice would be very much appreciated.

Jay

My 8120 ran great with G Skills but I couldn't get to the rated 2133 and the best I could muster was 1832 with tightened timings. If it was me I would run the 1866 and then tighten from there. In the end you're likely splitting hairs.

Run "winsat mem" from an elevated command prompt on both RAM configurations and see how much difference it shows.

Hi, thanks for your answer.

I ran winsat mem.

1866 11,10,11, 27 : 18176.48 MB/s
1600 9,9,9,24 : 18670.43 MB/s

Does this mean that it is actually faster at 1600 9,9,9,24?

I benched with SANDRA and got 21 GB bandwidth at 1866 vs 19 GB at 1600.

I just don't know enough to interpret these results properly!

How should I run my memory for best performance?

I'm no AMD expert, but I do believe I read something that said AMD CPU's could utilize a higher frequency set of RAM, so you might just want to keep it at 1866 and try to fiddle around with the timings like linnemeyerhere said.

Just in case you are wondering, the difference in those winsat scores more than likely isn't noticeable as far as just memory performance is concerned. You'll never be able to tell that it is running 500 MB/s faster or slower.

If I had it to do all over again this is how I would approach the ram game. I would purchase only sticks of matching ram all one time in the highest speed which I thought or others are telling me the mobo and cpu combo can realistically support. I would purchase the sticks in 8gb and if possible get 32gb loaded. Then I would as I've just done set up a ram drive. With 32 gb you could dedicate half to an amazing 16gb ram drive or more if it proved advantageous. I've added 4gb of my 16gb and the system is noticeably quicker...your mileage may vary but DDR3 ram is currently cheap and so ....why not ?

Thanks for your answers guys.

I've been trying to tweak the timings both in 1866 and 1600, and I don't seem to be able to get better than 10,11,10,27 at 1800 and 9,9,9,24 at 1600. Anything tighter, I get BSOD at boot or fail prime95 within the minute.
Winsat mem 20.6 GB at 1866 vs 18.5 GB at 1600.
Voltage is at 1.6V right now. Sticks are rated at 1.5V
Tried increasing DRAM voltage but same results.
Would increasing Vcore help, since memory controller is under more stress with all slots in use? Right now I'm at 1.404V under load. Can't get it stable if I set it any lower. Temps are 33C idle, 53C load (1 hour prime95 blend)
Should I be trying to adjust any sub-timings, latencies, or anything beyond main CL timings?

Thanks,

Jay

BTW, I've set up a ramdisk as per your suggestion, using Primo Ramdisk Ultimate Edition. Amazing piece of software!
I've moved my Windows temp folders and FF cache to the ramdisk to keep writes to mi SSD as low as possible.
Do you know if it is possible to move the Windows page file to a RAM drive? If so, would it help performance beyond reducing writes to SSD?

Tried running without a page file, seemed to work fine, but some games just failed to start and asked me to set up a page file.

Any advice as to further possible optimizations to improve Windows/SSD performance?

The higher spec FX processors are built to support 1866 native ram speed.

I run run 2x8gb GEIL cas9 at 1866 with no problems.
Benching at 7268 MB/s

The newer AMD FX processors are being built to support 2100 native speed ram (including the successor to trinity APU)

I don't see a big impact on using 1866 vs 1600 if you get good ram with a good heat spreader doesn't matter at that point you can overclock to get the desired results but currently

the topping point to the fx series is 1866 it might support higher on OC but it is really hard to crank ram to the rated speed if you hit the max chip potential

im running 16 gbs of 1600 overclocked slightly and it's just as fast as someone using 1866 or 2100mhz

you will only get so much from ram the real boost would be the cpu and the time it takes the hdd to drum up the information