A64X2 4200+ memory-related OC questions

cr0ft

Junior Member
Aug 16, 2007
2
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I've been cheerfully running my 4200+ X2 at stock speeds without really thinking that much about it, but when I found myself contemplating whether or not I should go out and buy an Opteron 185 instead I figured I might as well take a look at OC'ing what I have, first.

So, I cranked the bus speed to 240 and hit 2.6 Ghz, and Prime95 started giving errors right away. I tried cranking voltage to 1.5 (didn't want to try higher) but still unstable, so I dialed the bus speed down to 230 and got 2520 MHz and it seems quite stable. That's with a multiplier of 11 and a voltage of 1.40 even.

The next step was to adjust K8 to SB to 4x, giving me a HT Link of 920Mhz which is perfectly fine, as I won't come close to saturating that even with gigabit network etc.

So much for background.

My questions concern RAM. When I left it in auto it ran at a laughable 133Mhz, so I cranked it to 166. At that speed, CAS is 2 with this memory which is good - but at 200MHz CAS goes to 2.5 and Tras goes from 7 to 8 (the latter has little performance impact I believe).

So, though I presume the answer is that I should run 200mhz (which comes to 230 according to CPU-Z with this oc) and eat the 2.5 CAS instead of 2 I figured I'd ask - is that true?

Another issue I wasn't really even aware of was the 1T vs 2T thing. My old S939 mobo was running with 4 x 512, and I migrated that. This means that the board I'm using (A8N32-SLI Deluxe) autoselects 2T and trying 1T manually of course didn't work.

How much of a performance hit do I take running with 4 chips? Does the fact that I have now clocked the memory at 230 Mhz make up for that at all? Should I in fact just go out and buy two 1GB sticks instead?

Thanks for any input here.
 

BitByBit

Senior member
Jan 2, 2005
474
2
81
Assuming you're running a S939 system, your DRAM : HTT ratio should be 1:1, meaning in this instance your memory should be running at 230MHz (DDR460) - the same as your HTT.
Regarding CAS latency vs frequency, bear in mind that real latency is determined by both the CL and frequency.

Latency = CL / Freq.

At 166MHz and CL 2, your latency is ~ 12ns. At 200MHz and CL2.5:
2.5 / 200MHz = 12.5ns.

So, the initial configuration will give you the lowest latency (albeit by an insignificant amount), but the latter will give you the most bandwidth and will likely give you the most performance.

On the subject of command rate, you would be forced to run at 2T if you used 4 sticks of RAM, not that it makes much difference to performance. Personally, I'd buy two 1GB sticks before DDR starts getting scarce.
 

cr0ft

Junior Member
Aug 16, 2007
2
0
0
Ah, thanks for the math lesson. :) Yes indeed, this is a S939 system. That means that I should obviously run the memory at 200 (ie 230)Mhz, which is what I'm running now, so I guess I stumbled over the correct setting after all.

Yeah, I'm stuck at 2T I guess, and that will have to do for now. Buying two 1GB sticks would cost too much for the benefit it gave, next time I buy something it will be an entirely new mobo/cpu/memory combo - for now, this system will do for everything I want to do with it, especially with 300 fresh MHz squeezed out of the CPU as well as the speed increase on the RAM.

Thanks again for the input.