A few RAM questions

[FOF]

Hi all

Please forgive my ignorance here, but I have a few burning questions about RAM I need answered.

1) Firstly, I see many folk buying say, DDR500 or 433 Mhz RAM, yet as far as I know, most mobo's support only up to 400 Mhz RAM speeds. Is there any real justification for buying RAM that fast?

2) What is the difference between dual DDR and single DDR
RAM?

3) I've recently seen a lot of posts about RAM timings (ie. 2-2-2-5 or something similar) - what does that actually mean and how do I check my RAM timing?

4) Does system RAM compensate for low video RAM? What I mean is, say my video card RAM is being heavily taxed by a game, is system RAM brought in to help load textures etc?

For the record, I'm running and old Athlon 2000XP (Palomino) with 512Mb Transcend memory, but am thinking of upgrading to an Athlon 64 with 1 Gb DDR 400 fairly soon.

Again, forgive my ignorance. Hey, we all have to start somewhere, right?

 

[Crashman]

They support faster speeds because the faster memory supports slower speeds. The reason people buy PC4000 (DDR500) is for overclocking, it supports all speeds between DDR266 and DDR500.

2.) the modules are the same, some chipsets are able to use 128-bit access by pairing 64-bit modules, for 2x the bandwidth.

3.) Read Tom's article from around 8 months ago (I think) on RAM timings. Latency is measured in cycles, so lower number indicate quicker response times.

4.) Not automatically, but you CAN increase AGP Aperture which CAN help with textures on a limitted card, but that also depends on the game being written for it.

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[FOF]

Ok, thanks.

Concerning point #2: Would an Nforce 3 chipset (For the socket 939 AMD 64's) support dual DDR RAM then? If not, what chipsets do?

 

[Crashman]

The memory controller of A64's is built into the CPU rather than the chipset, so that's really a CPU issue. Socket 754 chips didn't support dual channel operation, but I've heard Socket 939 chips do.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

 

[jammydodger]

Yeh I think all the Socket 939 Athlon64's will support dual channel. The FX definatly does.

Regarding question 4, you have to remember that the maximum possible memory bandwidth for a non-overclocked Athlon system is 3200MB/s. It sounds like a lot but w modern graphics cards have 256bit memory buses that can transfer at upto 20,000MB/s. Thats 6 times faster than the system memory, so if large textures need to be loaded from RAM in a hurry performance will be sacrificed.

 

[FoodHULK]

ive recently bought an amd 3200+ with a nforce 3 250gb mobo and i think my ram problems is probably todo with whats being said. ive got some budget pc3200 ram with 3,3,3,5 ratings and on sisoft sandra its memory bandwith is: 2858 mb/s. If 3200 is the maximum what can i do to get a figure more like this?