Command rate A64?

[speedy_s]

Can cheap memory be ran on 1T command rate on a64 on stock settings?
Thanks

[Olly1234]

How cheep are you looking at?

[speedy_s]

crosair value select

[Olly1234]

Yep at these timings which arent bad to be honest 2.5-3-3-7-1T

[nvening]

can u explain what the hell 1T command rate is? thx

[Olly1234]

Sure

This delay is between the sending of the Chip Select signal till the time the memory controller starts sending commands to the memory bank. The lower the value, the sooner the memory controller can send commands out to the activated memory bank and thus the faster your memory is

With 1T, the memory controller will only insert a command delay of one clock cycle

With 2T the memory controller will insert a command delay of two clock cycles

If the SDRAM command delay is too long, it can reduce performance by unnecessarily preventing the memory controller from issuing the commands sooner. However, if the SDRAM command delay is too short, the memory controller may not be able to translate the addresses in time and the "bad commands" that result will cause data loss and corruption...Simple

[nvening]

What is the chip select signal and i heard of it but what exactly is a memory contoler and whats the memory bank? Also i know what the first number is and i guess after this the last but what are the ones in between? eg 2.5-3-3-7-1T Man, RAM seems to be more complicated than i though.

[Olly1234]

The Asus Sli Dram config page is huge now, has about 10 different ram options, my nf7 only has about 3, god only knows what they all do, will find out though :-)

Memory controler is the thing that generates the signals to control read and write, memory bank is the ram on your sticks, ram is always read in tRAS-tRCD-tRP-CAS, so actaully it should have been writen 7-3-3-2.5

The first is tRAS, or Row Access Strobe. It is the number of cycles that the RAM has to read the data from a block of memory. The space between a request for a block of data, and the actual reading operation is called tRCD. CAS latency is the amount of cycles during which the exact portion of memory the system is looking for within the open memory bank is isolated. Finally tRP acts as sort of the ‘ending’ of the process; the time allowed for the memory to close the open bank and be ready for a new request.

[nvening]

so n an ideal world what would these readings be?

[Olly1234]

Low as possible mate 5-2-2-2 although for Nvidia chipsets they like large tras so 11-2-2-2 but you need good ram to get those timings

[Rave]

5-2-2-2 is actually a technically incorrect setting. tRAS should apparently be CAS + tRCD + 2 so 2-2-2-6 would be correct, or 2-3-3-7 etc. In practice A64s tend to perform best at with a tRAS 10 for some reason (irrespective of chipset, since the mem controller is on the CPU).

Thanks for explaining command rate olly, good to have a knowledgeable chap like you around.

Rich :¬)

[Olly1234]

Ahh silly me, had forgotten the old formula.doh..Cheers Rich

[BUFF]

5-2-2-2 is actually a technically incorrect setting.

but it still gives the best results for some people depending upon RAM, board etc.

[Fresco]

Very nice info, i never really understood RAM

So the timings quoted my manufacturers, eg Corsair XMS3200XL Pro with timeing of 2-2-2-5 is the maximum rated at stock speeds? Should I be tweaking the timings on an A64 board to be 2-2-2-6 or even 2-2-2-11? Very confused

[Olly1234]

Yep thats the max before the memory will stop working error free, intel work better at low tras but AMD64's get higher bandwith with a tras between 10-15, find about 11 works well for me on mine, of course if your going to overclock above rated speeds yiou'll need to losen off the timings generally, and also watch the ratings on memory on websites as they are usually based on running in intel based boards whereas in the small print youl see dual channel DDR timing might be a bit less for AMD