Phenom II Memory Speeds

[mark rumsey]

Don't ask me how I managed to miss it before, but I've just read the pinned post about the problems with memory speeds on AM3 CPUs, and it perfectly explains the problems I've been having since I bought my GA-MA790FXT-UD5P mainboard and Phenom II X4 955BE  processor last year. I have 8GB (4x2GB) of Corsair DDR3 1600MHz memory installed running at 1600MHz with the voltage at the recommended 1.8V. 90% of the time the PC runs quite happily, but now and again I get a BSOD crash, and when this happens I tend to get it 3 or 4 times in a row, then it clears and all is OK again. This is almost exactly what is described in the pin post, and also as described memtest cannot find any problems, and if that's not enough the BIOS SPD tries to clock the memory back to 1066MHz. According to Corsair the memory timing should be 9-9-9-24T at 1600MHz. So, I'm after some help. What speed should I run the memory at and what timings should I use? SPD suggest something like 7-7-7-21T (can't remember exactly). I'm running at standard clock speeds across the board for reliability and long life with a view to overclocking later on if I start to run things that are a bit more intensive. The other option I have would be to change the processor for a newer one (Phenom II X6) if AMD have now fixed the memory controller problems. Anyone got any ideas on this?

Thanks in advance

Mark

[autotech]

First off i use a different processor but i run at 9-9-9-24 / 2T / unganged at 1600 and it works for me no crashes at all it did when i was running ganged but once i changed to unganged problems went away.

Now a fact i know it is better to run at 1333 and tighter timings if you can say 8-8-8-24 or even 7-7-7-24, If you can run at 1066 and 7-7-7-24 2T unganged it will probably be as fast or faster than 1600 at 9-9-9-24 2T.

This is all up to you i used that quad core and i know when i had it 1333 was the best i could do and that was at 8-8-8-24 once i upgraded to the 1090t i went to 1600 and 9-9-9-24 2T Even though i know it stresses the cpu i upgrade alot until now it seems im happy where it is and the bulldozier isnt an improvement from what i have read.

[Dark Mantis]

Hi

As autotech has already mentioned the tighter timings will actually result in a faster throughput of data than sheer speed. If you can get your memory  to run at 7-7-7-21 that would be very good and fast. Try it and see, if you have problems with that you can loosen them a little and try again. You don't say which particular Corsair modules you are using but if it is the Dominators you certainly shouldn't have much trouble.

[absic]

Hi Mark,

The problems with RAM speed are more noticeable on the AM3 Athlon chips and also with the Phenom ii's with C2 or C3 stepping which your 955 has and not so much on the X6 CPU's which have E0 Stepping. That said, running anything above 1333MHz RAM is technically overclocking the CPU and there is a risk if you do so.

Reading your post I am concerned at the high 1.8V that you say is the default for your modules as I have used many kits of Corsair RAM and have never had to go above a Corsair specified 1.65V even with Dominator so it would be good if you could post back with the exact RAM kit that you are using. The nearest I can find is this 4GB Kit that runs at 1.9V  http://www.scan.co.uk/products/4gb-(2x2gb)-corsair-xms3-ddr3-pc3-12800-(1600)-non-ecc-unbuffered-cas-7-7-7-20-dhx-19v are these the modules you are running? Are you running a single kit or did you buy two kits to get the 8GB of RAM?

[Dark Mantis]

Wow, I just looked at the RAM you posted there absic and what a price! It is good quality but at a rather high premium.

[mark rumsey]

When I bought the RAM last year I think it was nearly cutting edge stuff. It is two 4GB (2x2GB) kits from the 1600MHz XMS range kit part no. TW3X4G1600C9DHX. It looks identical to the kits on the scan website, but the specs are slightly different. At the time that was as much as would fit the motherboard as 4GB sticks were not available. The only differences between this and the slower 1333MHz kits (TW3X4G1333C9DHX) are the speed (obvoisly) and the rated voltage (1.8V against 1.5V). As I believe the only real difference is the 1600MHz modules were tested at that speed whilst the 1333MHz sticks were not, I'm guessing I could switch my modules down to 1333MHz @ 1.5V and see how it goes. If I do that, would it be best to stick with 9-9-9-24 or should I go straight to the auto SPD settings? I've checked and these arePC3-8500F 1066MHz 7-7-7-20 even though the sticks are definitely rated for the higher clock.

I've also come across a 16GB Corsair kit for under £100. This is the Vengance CMZ16GX3M4A1600C9 (4x4GB) which runs 1600MHz 9-9-9-24 @ 1.5V, and I guess would work fine at lower speeds with tighter timings. Has anyone tried these, and would they work with my system? I'm still on the F7 BIOS as it looked like the newer version did not have any fixes or advantages unless using newer 6 core processors. Your thoughts, as always, would be appreciated.

[Vezina]

I have XMS 3 /1600/ 2X4G too.
The Operating System is "strange" at 1600 Mhz ,i get various strange errors with some applications (Steam)  randomly though the RAM seems to be healthy .Most probable one stick to run 1600 Mhz only on C2/C3 cips.
When i put them on Auto they go to 1333 at 9-9-9-24T with 1T command rate .
I am running them for some weeks now like that with no serious issues.I have set the voltage to around 1,6 for the RAM and the NB VID (IMC voltage) to 1,175V (+0,075 V over the default for my CPU).

Put them on 1333 Mhz ,try 1 T and the "normal" 9-9-9-24 timings ,they should work just fine.
 

[mark rumsey]

Its been some time since I last posted here, so its about time for an update. Since my last post I've dropped the speed back to 1333MHz and I'm running 7-7-7-21T timings and it's been absolutely rock solid. No more blue screens, freezes during boot or other odd anomalies. Thanks to everyone for the help. Now all I've got to worry about are the 'normal' software problems which plague anyone running a Microsoft OS