Need faster RAM or not?

[Neverbehind]

Once I start building the system next week, my goal is to push 4400+ to 2.8 or higher with air cooling. Now, I understand that in order to do that I need to riase the FSB (or HTT), which could be limited by the RAM. So I need to either overclock the RAM or buy one rated at a higher speed. My concern is that spending extra money on faster RAM might be a waste if I can just overclock a cheap one. My question is that how stable can overclocking RAM be in order to push 4400 to 2.8 and beyond.

 

[exar333]

why not just use a divider? then you can use pretty much any RAM? although getting extra bandwith is always nice....i wouldnt shell out "uber bucks" for ram rated much beyond pc4000.....

 

[Neverbehind]

Well, I am gonna quote from Xtremesystems on divider

"Running the FSB and RAM with a ratio causes gaps in between the time that the FSB can communicate with the RAM. This causes slowdowns that wouldn't be there if the RAM and the FSB were running at the same speed. If you want the most speed out of your system, using an FSB:RAM ratio wouldn't be the best solution."

 

[Hacp]

Originally posted by: Neverbehind
Well, I am gonna quote from Xtremesystems on divider

"Running the FSB and RAM with a ratio causes gaps in between the time that the FSB can communicate with the RAM. This causes slowdowns that wouldn't be there if the RAM and the FSB were running at the same speed. If you want the most speed out of your system, using an FSB:RAM ratio wouldn't be the best solution."

Only true with processors that don't have HTT. To explain a little more, the "FSB" of the processor is ALREADY async with the fsb of the ram. With the ram dividier, I think you are just dividing the multiplier??? I'm not 100% sure someone correct me!!!

 

[RichUK]

Originally posted by: Neverbehind
Well, I am gonna quote from Xtremesystems on divider

"Running the FSB and RAM with a ratio causes gaps in between the time that the FSB can communicate with the RAM. This causes slowdowns that wouldn't be there if the RAM and the FSB were running at the same speed. If you want the most speed out of your system, using an FSB:RAM ratio wouldn't be the best solution."

Thats true but AMD has a different architecture that doesn't use an FSB, and therefore memory does not communicate on the FSB. AMD already has low latency communication with their on die memory controller, and thus using a divider will not have any major affect on performance.

However, myself i like to have my memory running 1:1 .. i would recommend some OCZ plat Rev 2's if you are looking to OC your memory (TCCD if you can find some, or DIMM?s with the newer TCC5 chips).

The average frequency range for the said RAM is 200Mhz to 270Mhz running at 1T command rate (i.e. PC3200 to PC4300, or PC4600 @ 2T).

Even when you OC this RAM to match the speeds of higher rated RAM, the timings are still comparable if not better (VX exceptions).

 

[KoolDrew]

Using a divider does not hurt performance.

 

[Furen]

Originally posted by: Neverbehind
Well, I am gonna quote from Xtremesystems on divider

"Running the FSB and RAM with a ratio causes gaps in between the time that the FSB can communicate with the RAM. This causes slowdowns that wouldn't be there if the RAM and the FSB were running at the same speed. If you want the most speed out of your system, using an FSB:RAM ratio wouldn't be the best solution."

There's no way to run an A64 at 1:1 FSB : DRAM ratio because the FSB (yes, these chips do have a frontside bus--or the equivalent, since there really havent been any "frontside buses" since the death of the backside ones and stupid slotA/1) is integrated into the core and runs at FULL CLOCK SPEED. That is, it runs at 2.2GHz on your 4400+ (at stock). Needless to say there's no ram that can run at 2.2GHz (that would be DDR4400) so your CPU always uses a divider. When running at the DDR400 setting, the divider your CPU uses is the same as the CPU multiplier. Using another setting just changes the CPU multiplier - Memory Divider ratio.

Just as an aside: The slowdown that occurs when you run Async in conventional FSB chips cannot happen at all in A64s because there are no non-integer memory dividers.

 

[imported_goku]

Originally posted by: ExarKun333
why not just use a divider? then you can use pretty much any RAM? although getting extra bandwith is always nice....i wouldnt shell out "uber bucks" for ram rated much beyond pc4000.....

Maybe you should explain to him the benefit of extra memory bandwidth.

 

[RichUK]

Originally posted by: goku

Originally posted by: ExarKun333
why not just use a divider? then you can use pretty much any RAM? although getting extra bandwith is always nice....i wouldnt shell out "uber bucks" for ram rated much beyond pc4000.....

Maybe you should explain to him the benefit of extra memory bandwidth.

there is non on A64's .. or atleast very little

 

[imported_goku]

but is that because the A64 already has tons of bandwidth already or is it for some other reason?

 

[Neverbehind]

You are right, get tighest timing with divider is the WAY to go!

 

[furballi]

Running 5:6 memory divider on an Athlon platform with cost about 50MHz of CPU core speed. With most quality value RAMs, a 5:6 memory divider will allow you to increase the speed from 200MHz FSB to at least 270MHz. That's a 35% overclock! Therefore, the 50MHz hit is VERY small compared to the gain in CPU core speed (FSB x CPU multiplier).

 

[n7]

A64s do benefit from higher RAM speeds, but they benefit far more from higher clock speeds.