Athlon 64 FX 51 mediocre performance on unbuffered memory -- WHY?

http://www.legitreviews.com/Reviews/reg_hyperx_2.shtml

The Athlon 64 FX 51 with dual channel PC3200 doesn't score remarkably well
on the UNbuffered Sandra memory test -- e.g. compared to a P4 with similar
dual-channel PC3200 DDR.

Why?

Is the Athlon 64 memory interface throttled to a lower total bandwidth? I
thought they were both (AMD and P4) ~ 6.2 GB/s max.

"H" == H W Stockman writes:

H http://www.legitreviews.com/Reviews/reg_hyperx_2.shtml The Athlon
H 64 FX 51 with dual channel PC3200 doesn't score remarkably well on
H the UNbuffered Sandra memory test -- e.g. compared to a P4 with
H similar dual-channel PC3200 DDR.

H Why?

H Is the Athlon 64 memory interface throttled to a lower total
H bandwidth? I thought they were both (AMD and P4) ~ 6.2 GB/s max.

The problem is the NVIDIA nForce 3 pro150 - TRY a VIA based
motherboard. VIA has better memory bandwidth. Hopefully the next round
of nvidia chipsets will have better memory bandwidth. It should be
noted that in real world usage users can't really tell the difference.

Actually according to some of the hardware review sites the SIS amd 64
chipsets have good memory bandwidth also.

Good luck

"Post Replies Here Please" wrote in message
...
"H" == H W Stockman writes:
[...]
The problem is the NVIDIA nForce 3 pro150 - TRY a VIA based
motherboard. VIA has better memory bandwidth. Hopefully the next round
of nvidia chipsets will have better memory bandwidth. It should be
noted that in real world usage users can't really tell the difference.

Actually according to some of the hardware review sites the SIS amd 64
chipsets have good memory bandwidth also.

Do you know of any tests of UNbuffered memory performance for the other
chipsets (on the web)?

I've looked high and low, and have found zilch.

"Post Replies Here Please" wrote in message
...
"H" == H W Stockman writes:

H http://www.legitreviews.com/Reviews/reg_hyperx_2.shtml The Athlon
H 64 FX 51 with dual channel PC3200 doesn't score remarkably well on
H the UNbuffered Sandra memory test -- e.g. compared to a P4 with
H similar dual-channel PC3200 DDR.

H Why?

H Is the Athlon 64 memory interface throttled to a lower total
H bandwidth? I thought they were both (AMD and P4) ~ 6.2 GB/s max.

The problem is the NVIDIA nForce 3 pro150 - TRY a VIA based
motherboard. VIA has better memory bandwidth.

That comment surprises me. Since the memory controller is part of the chip
with the Athlon 64 (i.e. its not part of the northbridge), then how can one
FX51 chipset have better memory performance than another? It doesn't make
sense, its got nothing to do with the chipset, surely?

I thought the different Athlon chipsets only differeed in terms of their AGP
performance, northbridge-to-southbridge performance, and southbridge
performance. But I am struggling to see how they would have different
memory performance, since none of them go anywhere near the memory.

Perhaps I misunderstand something?

Chip

"Chip" wrote in message
...

That comment surprises me. Since the memory controller is part of the
chip
with the Athlon 64 (i.e. its not part of the northbridge), then how can
one
FX51 chipset have better memory performance than another? It doesn't make
sense, its got nothing to do with the chipset, surely?

That was my impression too, but I admit not being up on all the gewgaws.

I was hoping that a few people with other FX 51 motherboards would post some
UNbuffered Sandra benchmarks, showing better performance. I've posted
benchmark requests in many groups; so far, no interest in UNbuffered tests.
I am beginning to think that (1) the market is so fragmented, and only a
very small number have the boards... or (2) the FX 51 doesn't do well on
this test, so people are reluctant to highlight a weakness of the
chip/board.

"Chip" wrote in message
...

[...]
That comment surprises me. Since the memory controller is part of the
chip
with the Athlon 64 (i.e. its not part of the northbridge), then how can
one
FX51 chipset have better memory performance than another? It doesn't make
sense, its got nothing to do with the chipset, surely?

Here's the first hint of an explanation...
http://www.lostcircuits.com/memory/reg_ddr/5.shtml

On Sat, 17 Apr 2004 18:08:28 +0100, Chip wrote:

That comment surprises me. Since the memory controller is part of the chip
with the Athlon 64 (i.e. its not part of the northbridge), then how can one
FX51 chipset have better memory performance than another? It doesn't make
sense, its got nothing to do with the chipset, surely?

The Hypertransport link of the NF3-150 chipset will only run at 600MHz.
3/4 speed iow's. VIA, SIS, and Ali run at full speed (800MHz).

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
http://mysite.verizon.net/res0exft/cpu.htm

"Wes Newell" wrote in message
newsan.2004.04.17.23.50.38.332793@TAKEOUTverizon .net...
On Sat, 17 Apr 2004 18:08:28 +0100, Chip wrote:

That comment surprises me. Since the memory controller is part of the
chip
with the Athlon 64 (i.e. its not part of the northbridge), then how can
one
FX51 chipset have better memory performance than another? It doesn't
make
sense, its got nothing to do with the chipset, surely?

The Hypertransport link of the NF3-150 chipset will only run at 600MHz.
3/4 speed iow's. VIA, SIS, and Ali run at full speed (800MHz).


What does the hypertransport link have to do with the MCT (memory
controller)?

On Sun, 18 Apr 2004 00:29:56 +0000, H.W. Stockman wrote:


"Wes Newell" wrote in message
newsan.2004.04.17.23.50.38.332793@TAKEOUTverizon .net...
On Sat, 17 Apr 2004 18:08:28 +0100, Chip wrote:

That comment surprises me. Since the memory controller is part of the
chip
with the Athlon 64 (i.e. its not part of the northbridge), then how can
one
FX51 chipset have better memory performance than another? It doesn't
make
sense, its got nothing to do with the chipset, surely?

The Hypertransport link of the NF3-150 chipset will only run at 600MHz.
3/4 speed iow's. VIA, SIS, and Ali run at full speed (800MHz).

What does the hypertransport link have to do with the MCT (memory
controller)?

Nothing, other than that's why the system performance is lower with the
NF3-150 chipset.

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
http://mysite.verizon.net/res0exft/cpu.htm

"Wes Newell" wrote in message
newsan.2004.04.18.05.57.20.161997@TAKEOUTverizon .net...
On Sun, 18 Apr 2004 00:29:56 +0000, H.W. Stockman wrote:


"Wes Newell" wrote in message
newsan.2004.04.17.23.50.38.332793@TAKEOUTverizon .net...
On Sat, 17 Apr 2004 18:08:28 +0100, Chip wrote:

That comment surprises me. Since the memory controller is part of
the
chip
with the Athlon 64 (i.e. its not part of the northbridge), then how
can
one
FX51 chipset have better memory performance than another? It doesn't
make
sense, its got nothing to do with the chipset, surely?

The Hypertransport link of the NF3-150 chipset will only run at 600MHz.
3/4 speed iow's. VIA, SIS, and Ali run at full speed (800MHz).

What does the hypertransport link have to do with the MCT (memory
controller)?

Nothing, other than that's why the system performance is lower with the
NF3-150 chipset.

True. But the thread is discussing memory performance, not system
performance. Hence HW's question.

Chip.