Memory Bandwidth KT400

markodude · Feb 28, 2003

HI there people
I recently built a KT400 system and have a 2400+ in there (133FSB) running all stock with memory set to 200mhz (DDR400)

My Sisoft sandra memory scores are down at 1500mb/s, is this because of the FSB - Memory bottleneck, and if so would I be as well running my DDR at 266?

hitechjb1 · Feb 28, 2003

max Memory BW at 200 MHz (DDR400) = 200 x 2 x 8 = 3200 MB/s
max FSB BW = 133 x 2 x 8 = 2128 MB/s

It is limited by the FSB bandwidth. The top portion of the memory BW (3200 - 2128) ~ 1100 MB/s are wasted. The CPU cannot receive/send date at that rate.

I think you are correct that at such FSB speed, it makes no difference using DDR266 memory running at 133 MHz in terms of BW.

Maybe even a little bit better since FSB and memory are in sync @ 133 MHz (not 100% sure about this point). Would be interesting to see if you run a memory BW benchmark on this to see it can be higher than the 1500 that you got.

You have to run the FSB at 200 MHz to get all the DDR400 bandwidth, but I doubt the KT400 MB will be able to run at that speed.

markodude · Feb 28, 2003

It should do, I had my KT333 Epox 8k3a running over 200 a year ago, although this board will not let me change the multi on the 2400+, without bridge modification I am up the creek without a paddle.....never mind its my mates system I just built it for him!

hitechjb1 · Feb 28, 2003

Have you tried running FSB and memory in sync @ 133 MHz. Would be interesting to see if you run a memory BW benchmark on this to see whether it can be higher than the 1500 that you got.

markodude · Feb 28, 2003

I would ask him to do it but he doesnt know how to get into the BIOS

Shade00 · Feb 28, 2003

It would be interesting to see if running it in sync did up the performance quite a bit.

Running the memory Async tends to decrease performance. But what it's at right now is pretty pitiful, even for a Via chipset(hehe).

Get him to change it. Inquiring minds want to know

hitechjb1 · Feb 28, 2003

Shade00 said:
It would be interesting to see if running it in sync did up the performance quite a bit.

Running the memory Async tends to decrease performance. But what it's at right now is pretty pitiful, even for a Via chipset(hehe).

Get him to change it. Inquiring minds want to know

Just to bring up a point beyond the KT400. For dual channel (either Intel chipset or nforce2), if the FSB speed (BW) can be run MUCH HIGHER (say 50-100%) than the memory speed to absorb the parallel memory BW, then there is an advantage to run the FSB and memory in ASYNC mode.

Sonny · Feb 28, 2003

The KT400 is terrible at running asynchronous, synchronous is the way to go.

My KD7 - RAID running a 1700+ @ 11 X 200 with 2 X 256 XMS3500C2PT fastest timings available;

I don't have any photo editing software installed at the moment so I had to chop the images down in MSPaint so I can upload them to TFID

Shade00 · Feb 28, 2003

Wow, that is some awesome bandwidth!

walldow · Mar 1, 2003

Sonny said:
The KT400 is terrible at running asynchronous, synchronous is the way to go.

yes SONNY is corect. the kt 400 chipset loves to run in sync and loves low lattancey ram. but SONNY running case 2 on 3500 you should be getting alittle bit better scores.

i am running sammy ctl pc2700 insync @12x200fsb 2.95v with relaxed timings and can bench 3015 in sandra!

as for markodudes post you would be better running the ram insync will let you reach higher fsb speeds as long as youre componants can handle the strane. running sync takes stress off the ram leting you run tighter timings, also gaining bandwith.

-=A][A=-cazman · Mar 1, 2003

So sonny is your system stable at 200 fsb? You see I have the xp1700 B core and i'm wanting a motherboard that can hit 200fsb. I was thinking of getting that A7N8X Dx mb because of all the goodies on it and i'm pretty sure it can hit 200fsb. Also I'm not familiar with the KD7 does it have dividers so that your not OC'n your PCI and AGP buses?

Cheesy Peas · Mar 2, 2003

Sonny said:
The KT400 is terrible at running asynchronous, synchronous is the way to go.

My KD7 - RAID running a 1700+ @ 11 X 200 with 2 X 256 XMS3500C2PT fastest timings available

thanks for that sonny, im just off to set my kd7 at sync

cheers.

much better!! im gettin 2080 now instead of around 1800 before

Sonny · Mar 2, 2003

walldow said:
SONNY running case 2 on 3500 you should be getting alittle bit better scores.

i am running sammy ctl pc2700 insync @12x200fsb 2.95v with relaxed timings and can bench 3015 in sandra!

LOL!!! I wish :beer:

-=A][A=-cazman said:
So sonny is your system stable at 200 fsb? You see I have the xp1700 B core and i'm wanting a motherboard that can hit 200fsb. I was thinking of getting that A7N8X Dx mb because of all the goodies on it and i'm pretty sure it can hit 200fsb. Also I'm not familiar with the KD7 does it have dividers so that your not OC'n your PCI and AGP buses?

Yes it's stable & no the KT400 has no 1/6 divider so my PCI & AGP bus speeds are 40MHz & 80MHz respectively & I like it that way

I see no reason to keep them at default bus speeds. FSB overclocking with PCI & AGP locks are just wrong IMNSHO

Memory Bandwidth KT400

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