It is incredibly stupid Intel "engineer"/marketing terminology:Originally posted by: bomax
Can someone explain how the RAM speeds work in relation to the FSB on these C2Ds?
Haha, great explanation, Ron. The only thing you forgot to tell him is that on some motherboards, instead of it being called the 1:1 memory ratio, it's called the 266 Mhz or the 533 DDR memory ratio. I think that all Asus boards call it the 533 ratio, for instance, even though the RAM is actually running at 266 Mhz, until you start overclocking.Originally posted by: RonAKA
It is incredibly stupid Intel "engineer"/marketing terminology:
If you look at CPU-Z on the first tab you will see the "Bus Speed". The CPU runs at a multiplier shown above this times the bus speed to give you the core (CPU) speed, or the commonly advertized speed of the computer. You overclock the cpu by changing the bus speed or multiplier or both.
If you look at the memory tab then you will see that the DRAM runs at the same bus speed times a FSBRAM ratio or multiplier. If this multiplier is 1:1 then the frequency of the DRAM is the same as the bus speed. Careful: note the FSB term is the same number as is called the bus speed on the previous tab!
But that would be too simple to end there. For whatever reason the rating of the DRAM to do this is double this frequency. So if your frequency of the memory is 400 MHz then you need DDR2-800 to ensure it will work without errors.
However, if you increase the voltage from the default 1.8v on the DRAM you are likely to get more than the rated speed out of the memory. The other trick of course is to increase your CPU speed and change your memory multiplier to keep the memory within frequency limits.
Make sense? Probably only to a "Intel engineer", or more likely the marketing dept!
I didn't want to get into that, but since you raise it, yes it appears the Asus "engineers" had to trump Intel on this one, for supreme stupidity. I can't say I have figured it out for sure, but by trial and error I think what they have done is take your default bus speed and the default DRAM speed and put in a multiplier to ensure on default auto DDR2-800 runs at 400, and 667 at 334.... That makes some good sense for out of the box performance. But to overclock it, you have to go from SPD to Manual and select another DDR2 speed which in effect really just changes the bus to memory multiplier. The only up side is that the BIOS will tell you what the memory will run at with a simulated DDR2 rating as you select different bus speeds. CPU-Z does as well, if you manage to boot up to display it.Originally posted by: myocardia
Haha, great explanation, Ron. The only thing you forgot to tell him is that on some motherboards, instead of it being called the 1:1 memory ratio, it's called the 266 Mhz or the 533 DDR memory ratio. I think that all Asus boards call it the 533 ratio, for instance, even though the RAM is actually running at 266 Mhz, until you start overclocking.
What's your mother's name? I think we might have been separated at birth!Originally posted by: RonAKA
I didn't want to get into that, but since you raise it, yes it appears the Asus "engineers" had to trump Intel on this one, for supreme stupidity. I can't say I have figured it out for sure, but by trial and error I think what they have done is take your default bus speed and the default DRAM speed and put in a multiplier to ensure on default auto DDR2-800 runs at 400, and 667 at 334.... That makes some good sense for out of the box performance. But to overclock it, you have to go from SPD to Manual and select another DDR2 speed which in effect really just changes the bus to memory multiplier. The only up side is that the BIOS will tell you what the memory will run at with a simulated DDR2 rating as you select different bus speeds. CPU-Z does as well, if you manage to boot up to display it.
Wouldn't it make some sense for the DRAM manufacturer to tell you what frequency it is really rated for, and the motherboard manufacturer to let you select that real frequency in the same terms (not double or half or some goofy proxy for a multiplier)???
Perhaps that would be too simple and everybody would OC their CPU and not buy the same version for more $$ that has it done for you.
Originally posted by: gramboh
I'm also assuming 1:1 is the best situation for overall performance. I'm going to be buying an E6600 with OCZ PC2-6400 Platinum Rev2 (or FlexXlc CL4) and hoping to run it at either:
1:1 8x 450FSB/memory (900MHz DDR, CAS5) = 3600MHz
1:1 8x 425FSB/memory (850MHz DDR, CAS4 or 5) = 3400MHz
1:1 8x 400FSB/memory (800MHz DDR, CAS4) = 3200MHz
depending on how my chip performs (crossing fingers). For these settings I'd leave it on 533 in the BIOS for 1:1 correct?
Originally posted by: yacoub
3GB of RAM? That could even be part of the problem... better to stick 2x1GB sticks than throwing in another 1GB or worse an additional 2x512MB. Try taking out the extra RAM. Also be careful with the voltages. Maxing out the RAM voltage could be very harmful to the RAM and the CPU shouldn't need too much voltage just to get to 3GHz.
Your processor has a X10 multiplier, so your bus is running at 340 MHz. With a 1:1 DRAM multiplier this is a DDR2-680. Yes a bit slow for DDR2-800, and you likely could get away with DDR2-667 and save some $$. I've ran mine there and the memory part works fine. Not sure what you mean by a 2.5 multiplier as the next choice. Those are not ASUS confusion terms. If this means 2.5 X 340 or 850, then yes I would have expected your DDR2-800 to get by with some extra volts. However, I think you said you were at +.4 already. Sounds very high if nominal is 1.8V? 2.2V is usually max.Originally posted by: bomax
Yes I hit the 3.4Ghz on 1.4v very stable... but that was with the mem ratio at 1:1, so my memory was only running at 340Mhz... too slow. When I increased the mem ratio to the next step (2.5 as listed in bios), it would not even boot (even after reducing FSB to 320Mhz resulting in RAM at 800Mhz -- stock speeds).
This is what led me to believe there is something I'm missing from the equation...
Originally posted by: GuitarDaddy
How do you have your ram installed? To get the full 3gb in dual channel you probably need 1x1gb + 1x512mb in each channel (same colored slots)
Post a screenshot of the memory tab in CPU-z if you can.
I'm using a Gigabyte mobo, and in the BIOS the memory multipliers are somewhat odd, it has 2 (which really means 1:1), and the next step up is 2.5. By changing to 2.5 it wouldn't even boot! I don't understand this since by reducing FSB to 320 this *should* mean the memory is running right at 800Mhz, or stock. Again, this is what made me originally believe I was missing something...Originally posted by: RonAKA
Your processor has a X10 multiplier, so your bus is running at 340 MHz. With a 1:1 DRAM multiplier this is a DDR2-680. Yes a bit slow for DDR2-800, and you likely could get away with DDR2-667 and save some $$. I've ran mine there and the memory part works fine. Not sure what you mean by a 2.5 multiplier as the next choice. Those are not ASUS confusion terms. If this means 2.5 X 340 or 850, then yes I would have expected your DDR2-800 to get by with some extra volts. However, I think you said you were at +.4 already. Sounds very high if nominal is 1.8V? 2.2V is usually max.
Have you tried loosening your DRAM timings to 5-5-5-15?