Q: Testing PC stability

[sinij]

I finally got some time to attempt overclock my sysytem... not surprisingly it got A LOT complicated since I did it last time on my P3.

I got CPU-Z utility to better understand all settings and noticed following:

Memory

DDR2 2048MB, Channels # Dual

Frequency 402.5Mhz
FSB:DRAM CPU/6
CAS Latency 5
RAS to CAS Delay 5
Cycle Time 12
Bank Cycle Time 23
Command Rate 2T

Now this does not look like anything I expected out of my memory settings. It correctly identifies CM2X1024-8500 Corsair modules but shows Max Bandwidth at PC2-6400 (400 MHz). Auto mode does not seem to work.

Manufacturer specifies that memory was tested at 5-5-5-15-2T 2.2V 1066Mhz....

Now in bios of my MB (M2N-SLI) it all set to auto. I can set memory clock frequency but max setting is DDR2 800 and I can also set rest of the things to 5-5-5-15-2T. What is not clear is how I can increase FSB and get it to run at 1066Mhz?

I read somewhere that DDR2 FSB tied to CPU frequency, is getting to 1066Mhz possible only via CPU overclocking? Anyone can link to good Windsor AM2 X2 OC guides?

Help! HEAL! My PC is PKing me.

[Trippy]

I read somewhere that DDR2 FSB tied to CPU frequency, is getting to 1066Mhz possible only via CPU overclocking? Anyone can link to good Windsor AM2 X2 OC guides?

Yes, you'll need to OC your bus speed from 200 MHz to 266 MHz, which will also OC your CPU, if you want to run your memory at 1067 MHz.

[Engels]

Yes, you'll need to OC your bus speed from 200 MHz to 266 MHz, which will also OC your CPU, if you want to run your memory at 1067 MHz.

[/quote]

Is bus speed the same thing as 'external clock speed'? I ask because my Asus OC utility program has a CPU setting thingajig that starts at 200 and goes up to 300+ or so, and its labled 'external clock speed'.

[Strazos]

If I remember correctly, External Clock Speed * Multiplier = FSB speed.

[Trippy]

Yes, you'll need to OC your bus speed from 200 MHz to 266 MHz, which will also OC your CPU, if you want to run your memory at 1067 MHz.

Is bus speed the same thing as 'external clock speed'? I ask because my Asus OC utility program has a CPU setting thingajig that starts at 200 and goes up to 300+ or so, and its labled 'external clock speed'.

If it's an A64/Opteron system and the default is 200 MHz then yes. There's no consistent name for it -- e.g. ASUS calls it "CPU Frequency" in some of their BIOSes and DFI calls it "FSB Bus Frequency" in some of theirs -- but it's the clock frequency that's used by the CPU and HyperTransport multiplier settings to determine their speed.

I also forgot to mention that with A64s you should be able to lower to the CPU multiplier (but you can't raise it unless you have an FX) so if you are having trouble overclocking the bus speed with the default CPU multiplier trying lowering the multiplier.

[Strazos]

What effect would lowering the multiplier have on CPU performance?

[sinij]

I read somewhere that DDR2 FSB tied to CPU frequency, is getting to 1066Mhz possible only via CPU overclocking? Anyone can link to good Windsor AM2 X2 OC guides?

Yes, you'll need to OC your bus speed from 200 MHz to 266 MHz, which will also OC your CPU, if you want to run your memory at 1067 MHz.

What about alternative approach of tighter settings at current bus speed? What will be overall more beneficial, say FSB 1066Mhz at  5-5-5-15-2T or FSB 800Mhz at 4-4-4-9-2T ? I found this article suggesting timings in some cases might have larger effect.

AS to OCing - I found a stub suggesting that my modules should run at DDR2-667, CL 3.0-3-3-8, 1.8V or DDR2-1000 CL 5.0-4-4-9 2.2v and maybe more if I'm lucky.

Would it be easier to get a MB that has DDR2-1000 setting? I'm still not clear what is difference between DDR2-800 and DDR2-1000. Are there any guides/write-ups that explains DDR2 memory overclocking so I can read it and stop asking stupid questions?

  It correctly identifies CM2X1024-8500 Corsair modules but shows Max Bandwidth at PC2-6400 (400 MHz). Auto mode does not seem to work.

Can someone explain to me how PC2-6400 (400MHz) that it shows at all related to 200Mhz FSB and 1067Mhz or 800Mhz that memory is rated at? Don't spare technical details.

[Trippy]

What effect would lowering the multiplier have on CPU performance?

Depends on what the bus speed is. E.g. for a 2.0 GHz A64 the default setup is a 200 MHz bus/clock and a 10x multiplier. If you leave the bus speed the same but reduce the multiplier obviously the CPU is going to run slower. Going back to sinij's question going from 200 MHz to 266 MHz bus/clock is a pretty hefty OC. That would mean our A64 would now be running at 2.6 GHz which isn't out of the realm of possibility but may be a stretch depending on the quality of the die. However if we reduced the multiplier to 9x that would only be 2.4 GHz.

[sinij]

I will try it tonight. Anything else I should be aware of, forgot to ask?

[Kenrick]

Out of curiousity... I've got DDR2-667 in my pc, so why does that program tell me my memory frequency is 334.5MHz?

[Trippy]

I read somewhere that DDR2 FSB tied to CPU frequency, is getting to 1066Mhz possible only via CPU overclocking? Anyone can link to good Windsor AM2 X2 OC guides?

Yes, you'll need to OC your bus speed from 200 MHz to 266 MHz, which will also OC your CPU, if you want to run your memory at 1067 MHz.

What about alternative approach of tighter settings at current bus speed? What will be overall more beneficial, say FSB 1066Mhz at  5-5-5-15-2T or FSB 800Mhz at 4-4-4-9-2T ? I found this article suggesting timings in some cases might have larger effect.

That's a DDR benchmark not DDR2. However for A64 systems generally, memory bandwidth is not an issue which is why AM2/DDR2 systems only benchmark slightly higher than the equivalent DDR system even though the theortical peak memory bandwidth is a lot higher which is why faster timings is often better. I haven't worked with any AM2/DDR2 machines so I can't say which would be better in your case but my guess is the faster timings would probably be better.

Would it be easier to get a MB that has DDR2-1000 setting? I'm still not clear what is difference between DDR2-800 and DDR2-1000. Are there any guides/write-ups that explains DDR2 memory overclocking so I can read it and stop asking stupid questions?

DDR2-1066 is meant for Intel systems. 266 MHz clock/bus frequency is not a natural one for A64 systems but it is for some Intel CPUs.

[Trippy]

Out of curiousity... I've got DDR2-667 in my pc, so why does that program tell me my memory frequency is 334.5MHz?

You can think of the "667" part of the chip description as the effective bandwidth in megabytes per second of that chip. The memory bus speed for DDR2 memory is actually half that number in MHz and even more confusing the chip is running at half the memory bus speed internally (which is different than DDR which is 1 to 1). Since each DIMM transfers 8 bytes per request the total bandwidth for that DIMM is 8 x 666.6 which is why you see the same DIMM referred to as PC2-5300 (5333 rounded down to the nearest hundred).

[Trippy]

Can someone explain to me how PC2-6400 (400MHz) that it shows at all related to 200Mhz FSB and 1067Mhz or 800Mhz that memory is rated at? Don't spare technical details.

For Intel systems you can read my reply to Kenrick.

For AM2 systems it's much more complicated -- I'm not sure I can explain it properly but I'll try. The CPU speed is determined by a multiplier multiplied by this clock thing that nobody can agree on a name for which by default runs at 200 MHz. The memory bus is connected to the CPU directly thanks to the on-chip memory controller. However the memory bus is not connected to the same 200 MHz clock that's driving the CPU (and HyperTransport) and instead derives its clock from the CPU frequency divided by an integer value. Back in the days of DDR this wasn't an issue because the max frequency DDR memory could run at (non-OC'd) was 200 MHz which happens to be the same as the clock speed driving the CPU so the memory bus divisor was the same as the CPU multiplier. With DDR2 memory, however, the memory clock frequencies start at and go higher than 200 MHz. So like I was explaining in my post to Kenrick you end up with something like this:

DDR2-400: memory bus clock at 200 MHz
DDR2-533: memory bus clock at 266 MHz
DDR2-667: memory bus clock at 333 MHz
DDR2-800: memory bus clock at 400 MHz
DDR2-1067: memory bus clock at 533 MHz

So to run DDR2-800 memory on an AM2 system at full speed you need to have a processor whose clock frequency is evenly divisible by 400 MHz otherwise it'll run the memory at something slower than the rated speed depending on what the closest integer divisor is that doesn't take the memory above its rated speed is.

[Kenrick]

head asplode.

[Engels]

So, on a related question, my motherboard came with a utility called NoS, which is Asus' 'easy' OC utility. It allows me to set the CPU total output increments by percentages, starting at 3%, ending at 10%. Am I correct in assuming that since I have a 939 chip that uses DDR memory, the multiplier is not being used, but that the original internal frequency of 200 mhz is being jacked up by small percentages? I ask because Trippy stated that DDR has a max frequency of 200, yet I don't think I can OC this CPU by raising the multiplier.

[Trippy]

So, on a related question, my motherboard came with a utility called NoS, which is Asus' 'easy' OC utility. It allows me to set the CPU total output increments by percentages, starting at 3%, ending at 10%. Am I correct in assuming that since I have a 939 chip that uses DDR memory, the multiplier is not being used, but that the original internal frequency of 200 mhz is being jacked up by small percentages?

Yes that's right.

I ask because Trippy stated that DDR has a max frequency of 200, yet I don't think I can OC this CPU by raising the multiplier.

I said non-OC'd DDR memory.

[Engels]

I said non-OC'd DDR memory.

Ok, so what's the difference between non-OC'd DDR memory and OC'd? Or do you mean something like, memory that's locked into a hertz rating no matter what? Cuz as far as I know, my corsair memory is nothing that particularly special.

[Trippy]

I said non-OC'd DDR memory.

Ok, so what's the difference between non-OC'd DDR memory and OC'd? Or do you mean something like, memory that's locked into a hertz rating no matter what? Cuz as far as I know, my corsair memory is nothing that particularly special.

Memory isn't "locked", it's just rated to run at a particular speed. If it runs faster than that then lucky you but it's still considered "overclocked" if it's running at faster than rated speed.

[sinij]

I decided that tighter memory timings are more important than high FSB speed, so I'm sticking to 4 4 4 12 and CPU multiplier at 12. Memory overheating, does it depend mostly on voltage? I never dealt with memory overheating before, would I pick up potential issues on motherboard temperature sensor?

So far I made a run at 4-4-4-12 2T, 12x multiplier and stock voltage of 1.264v for CPU with no heat issues under load that I could detect. Fastest stable CPU Clock multiplier with stock voltage is 210Mhz resulting in 2524Mhz CPU and 420Mhz memory speed. 5% oveclock reulting in CPU score increase to 1915 from 1834 baseline score from 3DMark2006. Next step is to figure out what is reasonable voltage boost and how much will it increase CPU temperature under load.

I will be repeating tests at 1T before I bump voltage.

I'm thinking hitting 1.4, maybe 1.45 vcore voltage with just air cooling. I have Thermaltake Mini Typhoon on CPU and 3 chassi fans. I set all fans for perfomance in BIOS.

Based on this article I should be able to hit 230Mhz (15% OC) before memory becomes a problem.

I need a better tool to measure results in order to evaluate lower multiplier 5 5 5 15 timings and very high bus speed vs. higher multiplier and lower bus speed. 1T vs 2T . Any suggestions?

[Sky]

There is a discussion of memory timings vs FSB in this month's Maximum PC.

[Kenrick]

There is a discussion of memory timings vs FSB in this month's Maximum PC.

When I skimmed over that post the first time I thought it said Maxim. 

[sinij]

AMD Athlon 64 X2 ADA4600CU voltage settings > me.

My experiments with voltage... System becomes unstable (won't even finish booting) at 1.300v, 1.325v, 1.350v. CPUZ tells me I have 1.264V to my CPU. Wiki tells me its 1.30-1.35v stock. Temperature never becomes an issue, its sits at 29-30C

WTF is going on? Help?

[Engels]

I suggest going back to BIOS defaults for everything, then looking at the voltage values they assign by default.

[Trippy]

AMD Athlon 64 X2 ADA4600CU voltage settings > me.

My experiments with voltage... System becomes unstable (won't even finish booting) at 1.300v, 1.325v, 1.350v. CPUZ tells me I have 1.264V to my CPU. Wiki tells me its 1.30-1.35v stock. Temperature never becomes an issue, its sits at 29-30C

WTF is going on? Help?

The Wiki is correct. When you have your Vcore set at Auto what does it report the Vcore to be in the Power/Hardware Monitoring tab in the BIOS? What does it report when you manually set it at 1.3 or 1.35?

[sinij]

Went back to 100% auto settings. Hardware Monitor reports 1.42V Vcore Voltage when in auto. It also reports 1.42V in 1.3-1.35v CPU voltage settings. CPUZ also does not change 1.264v 'measurment'. It seems to be stable at above 1.35v, will see what PRIME95 shows. It is stable in Auto.

Lesson of the day - do not trust utilities to tell you CPU voltage.

[sinij]

So far highest stable OC is 2580Mhz @ 1.465v 12x leaving me with 430Mhz memory @ 4-4-4-12 . It runs Prime95 without errors on dual cores and does not get past 55C 100% loaded.  When I boost voltage higher CPU starts ocasionally failing to post (any idea why?) and I get infrequent (once in 30 minutes) calculation errors in PRIME95. Since system stability is very important to me I chose not to go higher with CPU.

Video card is next. I figured out Coolbit setting for overclocking and it suggests 700Mhz memory and 550Mhz clock frequency. Will see how much boost it will give me.

So far I ran 3D mark, socre is 8394 (up from 7648 all stock).