Laptop memory upgrade: Can I mix DDR 266 PC2100 with DDR 333 PC2700?

I have an older Dell 600m laptop that I just figured out has 512 mb(2 x 256mb) DDR 266 PC2100 in it and I brought 1 Gb of DDR 333 PC2700 to exchange with one of the 256 mb modules to give me a total of 1.25 Gb. Can I mix these two types together? If so, what's the downside? Is it all just running at 266 rather than 333? If so, how much performance hit is this; enough to go out and get another 1 Gb of PC2700 to replace the remaining PC2100?


Thanks

 

In theory it should work. Why not give it a whirl.

 

Thanks. I tried it. Seems to work. It's showing all 1.25 Gb of memory.

What about performance of the two different speeds combined - much of a performance hit between 266 and 333 (I'm assuming it takes the 1 gb down to 266 rather than it's 333)? Is this a good combo or asking for trouble down the road?

 

Shouldn't be a problem mixing them but the downside is that everything will run at the DDR 266 speed instead of the DDR 333 speed that you paid for. You should see a performance boost just with the memory swap/increase, but I am not sure how much of a performance gain you will see between DDR 266 vs DDR 333.

 

First, you should check to see if your computer can even handle more memory (they all have maximum capacities per slot); otherwise, you're wasting money to put in more than it was designed to be able to accept.

My understanding is that while you can mix 2 different memory sizes (ie 1gb in one slot, 2in another), you are never supposed to mix 2 different memory types/speeds or they will oftentimes conflict because your BIOS is supposed to have a memory clock speed set of the actual RAM and 2 differing speeds=conflicting hardware from the BIOS end (it may still be fine as long as you keep it at the lower speed)... you can try and see if it has any fatal errors... in all reality, though, you're probably not going to get a speed improvement because in models that are older, the RAM performance was always bottlenecked by the front side bus speed-- what's your FSB speed for this comp? PC2100 memory is set to 133mhz, PC2700 to 166mhz... with DDR cards, you double the speed to 266/332, but that's where... if your FSB is only 100mhz, you'll only get 200mhz out of the RAM if it's DDR like the 2 you mentioned.

Not familiar with a 600m (you don't mean D600, do you?) so I can't say anything about what memory it can accept or its FSB (that would be in any kind of motherboard manual you might have or just look up your mobo and see its specs if you can find it anywhere, archived possibly), but sites like crucial can take your part number and get guaranteed-compatible memory options in case you haven't already used one of those tools.

Does that part make sense, or did I just run around in a circle with my head cut off?

As for the performance difference, the diff between 1.25 and 2gb (again, this is if your computer can even handle them!) is huge if you are a multi-tasker... but if you only have half a gig installed on a system that old, you'll be lucky if it reads 1gb. Another bios situation... but go into setup (instead of starting Windows--I assume XP?) and find your hardware's info in the bios... it will shed some light, or should, depending on how good the BIOS version is--some are better to get info from and change than others.

So my summary=try it, but don't expect the speed to be much help since your FSB isn't likely to be as fast as the new RAM if it's in that generation where the processors were way behind the memory. The FSB always bottlenecks when it's slower than the RAM or the CPU (and it's always slower than the CPU--the CPU will crunch data at its 1Ghz or whatever but it will only communicate with the rest of the computer at that bus speed--literally, the bus is taking the info to the other side, to the memory to have it temporarily stored while the CPU keeps working... then to the hard drive eventually for some of the data).

 

It will work fine, but you probably know this by now.
I have 2Gb of P3200 memory in my Dell inspiron 8500 and the system clocks it down to Pc2100 speeds, so all DDR memory is backwards compatible.
My timings rock, cause it is downclocked so much 2.5-2-2-5

K-TRON

 

What chipset? 915? If so 2GB max and not dual channel with DDR. If not which?

 

The chipset is Intel i855PM. The processor is Intel Pentium M 750 @ 1500 MHz. I'm running Windows XP SP3. I think, but am not sure, that the FSB is 133 mhz. Here's the text dump from CPU-Z to help since I'm a newbie on this stuff:

-------------------------
CPU-Z version 1.46
-------------------------

Processors Map
------------------------------------------------------------------------------------

Number of processors 1
Number of threads 1

Processor 0
-- Core 0
-- Thread 0


Processors Information
------------------------------------------------------------------------------------

Processor 1 (ID = 0)
Number of cores 1 (max 1)
Number of threads 1 (max 1)
Name Intel Pentium M
Codename Banias
Specification Intel(R) Pentium(R) M processor 1500MHz
Package Socket 479 mPGA (platform ID = 5h)
CPUID 6.9.5
Extended CPUID 6.9
Brand ID 22
Core Stepping B1
Technology 0.13 um
Core Speed 599.5 MHz (6.0 x 99.9 MHz)
Rated Bus speed 399.7 MHz
Stock frequency 1500 MHz
Instructions sets MMX, SSE, SSE2
L1 Data cache 32 KBytes, 8-way set associative, 64-byte line size
L1 Instruction cache 32 KBytes, 8-way set associative, 64-byte line size
L2 cache 1024 KBytes, 8-way set associative, 64-byte line size
FID/VID Control yes
FID range 6.0x - 15.0x
max VID 1.484 V
Features


Thread dumps
------------------------------------------------------------------------------------

CPU Thread 0
APIC ID 0
Topology Processor ID 0, Core ID 0, Thread ID 0
Type 01002001h
Max CPUID level 00000002h
Max CPUID ext. level 80000004h

Function eax ebx ecx edx
0x00000000 0x00000002 0x756E6547 0x6C65746E 0x49656E69
0x00000001 0x00000695 0x00000816 0x00000180 0xA7E9F9BF
0x00000002 0x02B3B001 0x00000000 0x00000000 0x2C043087
0x80000000 0x80000004 0x00000000 0x00000000 0x00000000
0x80000001 0x00000000 0x00000000 0x00000000 0x00000000
0x80000002 0x20202020 0x20202020 0x65746E49 0x2952286C
0x80000003 0x6E655020 0x6D756974 0x20295228 0x7270204D
0x80000004 0x7365636F 0x20726F73 0x30303531 0x007A484D

Cache descriptor Level 1 D 32 KB 1 thread(s)
Cache descriptor Level 1 I 32 KB 1 thread(s)
Cache descriptor Level 2 U 1 MB 1 thread(s)

MSR 0x000001A0 edx = 0x00000000 eax = 0x00111088
MSR 0x00000017 edx = 0x00140000 eax = 0xD00087B1
MSR 0x00000198 edx = 0x06100F31 eax = 0x06000610
MSR 0x00000199 edx = 0x00000000 eax = 0x00000610


Chipset
------------------------------------------------------------------------------

Northbridge Intel i855PM rev. A3
Southbridge Intel 82801DB (ICH4-M) rev. 01
Graphic Interface AGP
AGP Revision 2.0
AGP Transfer Rate 4x
AGP SBA supported, enabled
Memory Type DDR
Memory Size 1280 MBytes
Memory Frequency 133.2 MHz (3:4)
CAS# 2.5
RAS# to CAS# 3
RAS# Precharge 3
Cycle Time (tRAS) 6


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

DIMM #1

General
Memory type DDR
Manufacturer (ID) Hyundai Electronics (AD00000000000000)
Size 256 MBytes
Max bandwidth PC2100 (133 MHz)
Part number HYMD232M646D6-H
Serial number FFFF032B
Manufacturing date Week 32/Year 04

Attributes
Number of banks 2
Data width 64 bits
Correction None
Registered no
Buffered no
Nominal Voltage 2.50 Volts
EPP no
XMP no

Timings table
Frequency (MHz) 100 133
CAS# 2.0 2.5
RAS# to CAS# delay 2 3
RAS# Precharge 2 3
TRAS 5 6


DIMM #2

General
Memory type DDR
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 1024 MBytes
Max bandwidth PC2700 (166 MHz)
Part number VS1GSDS333

Attributes
Number of banks 2
Data width 64 bits
Correction None
Registered no
Buffered no
Nominal Voltage 2.50 Volts
EPP no
XMP no

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


Dump Module #1
0 1 2 3 4 5 6 7 8 9 A B C D E F
00 80 08 07 0D 09 02 40 00 04 75 75 00 82 10 00 01
10 0E 04 0C 01 02 20 C0 A0 75 00 00 50 3C 50 2D 20
20 90 90 50 50 00 00 00 00 00 41 4B 30 32 75 00 00
30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 CA
40 AD 00 00 00 00 00 00 00 01 48 59 4D 44 32 33 32
50 4D 36 34 36 44 36 2D 48 20 20 20 41 41 04 20 FF
60 FF 03 2B 00 00 00 00 00 00 00 00 00 00 00 00 37
70 49 34 35 53 30 31 31 38 32 2D 30 38 20 00 00 00
80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00


Dump Module #2
0 1 2 3 4 5 6 7 8 9 A B C D E F
00 80 08 07 0D 0B 02 40 00 04 60 70 00 82 08 00 01
10 0E 04 0C 01 02 20 F0 75 70 00 00 48 30 48 2A 80
20 75 75 45 45 00 00 00 00 00 3C 48 30 28 50 00 00
30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 68
40 7F 7F 9E 00 00 00 00 00 01 56 53 31 47 53 44 53
50 33 33 33 20 20 20 20 20 20 20 20 00 00 00 00 00
60 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
80 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
90 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
B0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
C0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
D0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
E0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00



DMI
------------------------------------------------------------------------------

DMI BIOS
--------
vendor Dell Computer Corporation
version A11
date 04/26/2004


DMI System Information
----------------------
manufacturer Dell Computer Corporation
product Inspiron 600m
version unknown
serial 5SNL051
UUID 44454C4C-5300104E-804CB5C0-4F303531


DMI Baseboard
-------------
vendor Dell Computer Corporation
model 0G5152
revision unknown
serial .5SNL051.CN4864345K3192.


DMI System Enclosure
--------------------
manufacturer Dell Computer Corporation
chassis type Portable
chassis serial 5SNL051


DMI Processor
-------------
manufacturer Intel
model unknown
clock speed 1500.0 MHz
FSB speed 133.0 MHz
multiplier 11.5x


DMI Port Connector
------------------
designation PARALLEL (internal)
port type Parallel Port PS/2
connector DB-25 female


DMI Port Connector
------------------
designation SERIAL1 (internal)
port type Serial Port 16550A
connector DB-9 male


DMI Port Connector
------------------
designation USB (internal)
port type USB
connector Access Bus (USB)


DMI Port Connector
------------------
designation MONITOR (internal)
port type Video Port
connector DB-15 female


DMI Port Connector
------------------
designation IrDA (internal)
connector Infrared


DMI Port Connector
------------------
designation Modem (internal)
port type Modem Port
connector RJ-11


DMI Port Connector
------------------
designation Ethernet (internal)
port type Network Port
connector RJ-45


DMI Extension Slot
------------------
designation PCMCIA 0
type PCMCIA
width 32 bits
populated no


DMI Extension Slot
------------------
designation PCMCIA 1
type PCMCIA
width 32 bits
populated no


DMI Extension Slot
------------------
designation MiniPCI
type 1
width 32 bits
populated no


DMI Physical Memory Array
-------------------------
location Motherboard
usage System Memory
correction None
max capacity 1024 MBytes
max# of devices 2


DMI Memory Device
-----------------
designation DIMM_A
format DIMM
type DDR
total width 64 bits
data width 64 bits
size 256 MBytes


DMI Memory Device
-----------------
designation DIMM_B
format DIMM
type DDR
total width 64 bits
data width 64 bits
size 1024 MBytes

 

An interesting side effect I noticed. Under the old RAM, it showed the processor was running at 1.39 ghz and now, with the new stick of RAM mixed with the old one, I'm showing the processor is running at 1.5 ghz. Why would the processor speed increase?

On another note, it looks like the max speed of the RAM in my system is 266 due to the FSB of 133. But, the timings between the two modules do not match at 266. Will this be a problem? Can I fix it? Any recomended tests on the RAM to see if it's going to work well together?


Thanks

 

DDR266 (PC2100), DDR333 (PC2700) and DDR400 (PC3200) SDRAM SODIMMs should be compatible with any system requiring those, even mixed. The advantage of going with faster memory, as it will tend to down clock to tighter timings. In your case, I would stick with just the 1GB stick of DDR333 until another stick is available. It’s just my opinion; the one stick of DDR333 would perform better than the DDR333/266 combo. If the other stick was at least 512mb in size, I would think differently since it would provide a nice balance on RAM.

 

I can't find the Intel document I wanted so I am going to have to wing it. Your chipset does not offer Dual Channel. Mixing should not be a problem but I would even though maybe not necessary. Put the larger in the primary slot (0). As at least with older non Dual Channel systems the primary is checked first. So have the larger with tighter timings as the primary. I see no drawback to having the 2nd DIMM in as when it is used, if not there would be a HDD hit and HDD hits are much slower than any RAM.

I have no explanation for CPU speed change? Have you repeated the setups and do they report the same?

 

Thanks. I originally put the 1GB module in the 2nd slot. I'll move it to the first slot as suggested. I may go pick up another 1Gb module to pair with it. It's only $20 after a $35 rebate but I really hate rebates. Plus, will I get much more performance from that second gig of memory over the 1.25 gb mixed combo I have in there now? I'm planning on replacing this laptop in about 6 months so trying to get the most from it without putting much money in it.

I don't get the CPU speed issue either. Really odd to me. I didn't mess with the bios when I put the new gig in. I just let the bios handle it automatically.

 

If you are going to replace in 6 months I think not worth it to get more. I assume you have XP and well that is enough RAM. I don't know things like if IGP shared memory but feel comfortable in saying regardless more RAM unlikely to help.