4 x DDR = Slower?

  • Thread starter Thread starter Paul Kelly
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Paul Kelly

I just updated my old p4 3ghz with MSI 875P chipset from 1 to 2gb of
memory. it had 2x512mb (PC3200 cas2) corsair twinx. now it has 4 of them.

suddenly the BIOS reports the memory speed as 266 (133 DDR) instead of
400DDR (200DDR).

take any of the two sets and its back to 400 again.

anyone know why this would happen?

Paul
 
I just updated my old p4 3ghz with MSI 875P chipset from 1 to 2gb of
memory. it had 2x512mb (PC3200 cas2) corsair twinx. now it has 4 of them.

suddenly the BIOS reports the memory speed as 266 (133 DDR) instead of
400DDR (200DDR).

take any of the two sets and its back to 400 again.

anyone know why this would happen?

Paul
Click to expand...

Because the memory buses can't make timing at 400mhz with more than two dimms
installed...
 
I just updated my old p4 3ghz with MSI 875P chipset from 1 to
2gb of
memory. it had 2x512mb (PC3200 cas2) corsair twinx. now it has
4 of them.

suddenly the BIOS reports the memory speed as 266 (133 DDR)
instead of
400DDR (200DDR).

take any of the two sets and its back to 400 again.

anyone know why this would happen?

Paul
Click to expand...

You are not on your own with this issue. It makes me ask why these
companies bother making the motherboard with 4 DIMM slots in the first
place?
 
looks that way :(
Click to expand...

Are those double sided DIMMs... i.e. you now have 4 ranks of memory on each
channel? Have you tried setting the timings and speed manually in BIOS
Setup: raise the CAS latency & other timings by a clock tick and then raise
the clock rate? Sometimes that'll work. I always advise people to get
single sided DIMMs now to help avoid bus load problems, such as those:
http://www.newegg.com/Product/Product.asp?Item=N82E16820146541
 
I always
advise people to get single sided DIMMs now to help avoid bus load
problems, such as those:
http://www.newegg.com/Product/Product.asp?Item=N82E16820146541
Click to expand...

I tried disabling SPD and setting 2-3-3-6, all boots ok but still 266.
this is a dump of my memory spd.

new ram : 200mhz = 2-3-2-6
old ram : 200mhz = 3-3-3-8

maybe this mix has forced the pc into some sort of compromise. i dont
know much about CAS/RAS Precharges. I had to look up the meaning of SPD

I think the answer would be sell the memory and stick to two 1gb modules
but its not really worth it on a 2 year old pc. think ill just wander in
the slow lane until those nice AMD socket 1207 board show up:)

Paul

Memory SPD
---------------------------------------------------------------------

DIMM #1

General
Memory type DDR-SDRAM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 512 MBytes
Max bandwidth PC3200 (200 MHz)
Part number CMX512-3200C2
Manufacturing date Week 00/Year 00

Attributes
Number of banks 2
Data width 64 bits
Correction None
Registered no
Buffered no

Timings table
Frequency (MHz) 133 166 200
CAS# 2.0 2.5 3.0
RAS# to CAS# delay 2 3 3
RAS# Precharge 2 3 3
TRAS# 6 7 8


DIMM #2

General
Memory type DDR-SDRAM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 512 MBytes
Max bandwidth PC3200 (200 MHz)
Part number CMX512-3200LL
Manufacturing date Week 00/Year 00

Attributes
Number of banks 2
Data width 64 bits
Correction None
Registered no
Buffered no

Timings table
Frequency (MHz) 200
CAS# 2.0
RAS# to CAS# delay 3
RAS# Precharge 2
TRAS# 6


DIMM #3

General
Memory type DDR-SDRAM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 512 MBytes
Max bandwidth PC3200 (200 MHz)
Part number CMX512-3200C2
Manufacturing date Week 00/Year 00

Attributes
Number of banks 2
Data width 64 bits
Correction None
Registered no
Buffered no

Timings table
Frequency (MHz) 133 166 200
CAS# 2.0 2.5 3.0
RAS# to CAS# delay 2 3 3
RAS# Precharge 2 3 3
TRAS# 6 7 8


DIMM #4

General
Memory type DDR-SDRAM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 512 MBytes
Max bandwidth PC3200 (200 MHz)
Part number CMX512-3200LL
Manufacturing date Week 00/Year 00

Attributes
Number of banks 2
Data width 64 bits
Correction None
Registered no
Buffered no

Timings table
Frequency (MHz) 200
CAS# 2.0
RAS# to CAS# delay 3
RAS# Precharge 2
TRAS# 6
 
I tried disabling SPD and setting 2-3-3-6, all boots ok but still 266.
this is a dump of my memory spd.

new ram : 200mhz = 2-3-2-6
old ram : 200mhz = 3-3-3-8

maybe this mix has forced the pc into some sort of compromise. i dont
know much about CAS/RAS Precharges. I had to look up the meaning of SPD
Click to expand...

Sometimes BIOS auto-settings just don't get it right. I'd say 2-3-3-6 is
way too ambitious here to get all 4 DIMMs working at DDR400; in fact there
are not many modules around which work at CASL=2 in any system. I'd start
with 3-3-3-8 and maybe even slower than that (3-4-4-10) and if possible
tighten back up when you get it working.
 
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