Overclocking RAM, latency confuses me.

[Werne]

Well, to be honest, I never actually overclocked RAM other than by accident when raising the FSB during CPU overclocking (FSB was the only thing I touched actually). But my PC now has a memory multiplier, and a CPU multiplier, so I decided to take my time and have fun with the RAM. :devil:

 

I've read a few so-called tutorials on that matter, and they all say the latency needs to be loosened up, and that I may need to fiddle with the voltage when overclocking RAM, also that BCLK can be raised for extra gain. So I went and tried...

 

I got two sticks of Transcend 1333MHz JetRAM, CL6. RAM's stock voltage is 1.500V, latency is 9-9-9-24 and the frequency is 1333MHz, so says BIOS. Those sticks were my spare RAM but since I needed the money, now it's my everyday RAM.

 

So far I was able to bump it to x8 from x6.66 (from 1333MHz to 1600MHz), it failed to boot on the first try and instead my second BIOS kicked in. So I loosened up the latency to 12-12-12-32, got a kernel panic, raised the voltage to 1.550V, booted like a charm. Ran a 2-hour Prime95 Blend test, no problem at all. Memtest86 doesn't see the RAM, but then again, it never did see the bloody RAM anyway, that thing never did work right for me. Maybe I loosened the latency too much, but I got no freakin' idea.

 

PC appears to be snappier now, shaved a few seconds off the boot sequence and programs seem generally more responsive. None too shabby. :cool:

 

 

 

However, there's one thing that bothers me and I can't figure it out - the latency. I know what it is (well, more or less), but I can't seem to find any information about loosening it up. The way I did it is that I raised the 9 up to 12, then calculated the increase percentage (33.3%) and raised the 24 to 32 (by 33.3%). I know how to overclock a CPU, but RAM? Nope.

 

Either way, the following works fine (better than it did in the first place), and I'd like to push this thing to 1866MHz if possible. But this latency thing is killing me, so I'd like to know a few things. Is there a correct way to loosen them or is it a hit-and-miss procedure? Do I need to loosen them up by a lot or by a bit? And is there anything else I need to tweak? Did I actually do it right? And finally, is there something I can f*** up by fiddling with the latency (I know I can f*** up with the voltage)?

 

All help is appreciated. :smile:

 

EDIT: Hmm, raised it to x9.33 (1866MHz) without touching anything else, Prime95 is running for about 45 minutes now, all good so far. I'll let it run for another hour or so, just to be sure it works without issues, then I'll try 2133MHz, just for s**ts and giggles.

 

EDIT 2: Well, 2133 is a no-go, won't even boot, just keeps telling me the PC couldn't start up and the second BIOS kicks in. Ah well, who cares. 1866 works with 12-12-12-32 like a charm, I tried tightening the latencies but, well, OS starts crashing then, likely do to the fact that I got no idea what I'm doing. :laugh:

Edited October 31, 2013 by Werne

[FMod]

The combined seconds of application productivity and even reduced frametime you'll save overclocking your ram will probably total to less than the time expended to write this post, let alone actually run all the tests.

 

However, there's one thing that bothers me and I can't figure it out - the latency. I know what it is (well, more or less), but I can't seem to find any information about loosening it up.

Assuming your actual RAM isn't getting any faster, only the bus, you would keep ~same latency in nanoseconds.

To find it, divide your dimensionless timings by the clock rate in GHz.

 

e.g. 9/1.333=6.75

thus at 1600 set same timing 6.75*1600=10.8 ~= 11 or aggressively 10.

 

This is approximate. Get your timings from articles on memory o/c referring to your specific make of chips (not sticks, chips).

[Werne]

The combined seconds of application productivity and even reduced frametime you'll save overclocking your ram will probably total to less than the time expended to write this post, let alone actually run all the tests.

I knew that even before I started doing this, but I'm doing it for fun and to learn a bit about it, I'm not actually interested in any gain. But I did try and see what I got with this, which is ~1.16%. Dat speed... :laugh:

 

Assuming your actual RAM isn't getting any faster, only the bus, you would keep ~same latency in nanoseconds.

To find it, divide your dimensionless timings by the clock rate in GHz.

 

e.g. 9/1.333=6.75

thus at 1600 set same timing 6.75*1600=10.8 ~= 11 or aggressively 10.

 

This is approximate. Get your timings from articles on memory o/c referring to your specific make of chips (not sticks, chips).

The calculation seems to be pretty accurate in my case, at 1600MHz the lowest values I can use without boot failure are 10-10-10-28, and on 1866MHz it's 12-12-12-33, but those tend to crap out from time to time. The results from that calculation are 11-11-11-29 for 1600 and 13-13-13-34 for 1866, and those are so far completely stable.

 

The chip make is, well, unknown. I can't find any precise information regarding these things other than the model of the module, which I already know. And even searching that, there's no information on overclocking them. Bummer.

 

Ah well, doesn't matter anyway, I achieved my pointless goal. :smile: Thanks for the help man, I'd give you kudos but I already did almost two years ago.

[AceGoober]

Need clarification:

 

I got two sticks of Transcend 1333MHz JetRAM, CL6

 

 

CL6 refers to CAS Latency 6. Or, the first number in the timings (example: 6-9-9-24)

 

If the RAM is actually CL6, or alternative description CAS 6, then at stock settings Windows general operations should have been snappy depending upon the rest of your system specs.

 

Getting 1866 Mhz out of that particular RAM is pretty good. One of the key settings, if your motherboard BIOS lists it, is VCCT voltage. Set this anywhere between 1.09 and 1.1 and you could possibly get 2000 Mhz out of those sticks with relaxed (12-12-12-38) timiings or 1866 with tighter timings (11-11-11-31).

[Werne]

Need clarification:

I got two sticks of Transcend 1333MHz JetRAM, CL6

CL6 refers to CAS Latency 6. Or, the first number in the timings (example: 6-9-9-24)

 

Ah yes, it's actually CL9, I was working with some numbers at the time and got confused, sorry about that.

 

Getting 1866 Mhz out of that particular RAM is pretty good. One of the key settings, if your motherboard BIOS lists it, is VCCT voltage. Set this anywhere between 1.09 and 1.1 and you could possibly get 2000 Mhz out of those sticks with relaxed (12-12-12-38) timiings or 1866 with tighter timings (11-11-11-31).

The VCCT voltage, there's no such thing in my BIOS, Google doesn't give any info on that either. I'm guessing you meant "VTT Voltage" which is set to 1.050V. As far as I understand, that's memory controller voltage on Intel CPUs, and something about termination logic on AMD CPUs, and I have an AMD FX 8320. The AMD equivalent of Intel's VTT is VDDNB, which provides voltage for HyperTransport and L3 cache.

 

Problem is, I never had an AMD CPU before so I got no idea what needs to be adjusted, there is no option saying VDDNB and no description on what any of the specific voltages are. But now you got me thinking, so it's time to dig through BIOS and manuals again.