4 GB 1066 or 6 GB 800

Depends what's more important to you - size or speed  

4GB is quite a bit, and if you are using a 32 bit operating system, it's all you can use (6GB is not very useful in a machine running a 32 bit OS). I'd lean towards using the 4GB.

From experience...

32bit Windows: Install 4GB and you will only see about 3.25. Thats as good as it gets.

64bit Windows: Anything above 4GB helps, 8GB is reasonable unless your are running Virtual Machines.
1. Size matters more than speed.
2. Windows limits for x64 Vista/7 Home 8GB, Home Premium 16GB, Business/Pro/Ultimate 128/192GB.
3. In real life I find it difficult to use more than 10GB.
4. Be aware that your pagefile should be at least equal to your memory size.

Jerry Adams

FYI: x64 Windows Server, SBS 2008, & SBS 2011 all want more than 8GB, 16 to 32 is reasonable.

The differences in speed between DDR2 800 and 1066 is negligible 1-3%, and combined it would all have to run DDR2 800. Example -> http://images.anandtech.com/reviews/memory/ddr2/2006/pa...

The 'problem' is in mix-matching Frequency and CAS Timings; I assume the Voltages are identical otherwise forget it.

DDR2 800 4-4-4-12 @ 1.8v
DDR2 1066 5-5-5-15 @ 2.2v ; review the JEDEC 800 CAS Timings & Voltage per CPU-z
====================
DDR2 800 5-5-5-15 @ 2.0v ; and hope the Voltage disparity works

Worst, Mix-Matching tends to lead to excessive errors for the advantages are gone if that's the case.

IMO - run the 'G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066' by itself and obviously >4GB requires a 64-bit OS.

Hi,

The OS is Windows 7 64-bit (Ultimate)....my main concern was both set are the different voltage DDR2 800 at 1.8 & DDR2 1066 at 2.0 to 2.2 & I don't think that they will work together that well & is there a huge difference between 4 GB 1066 & 6 GB 800, other wise i will drop 2 GB(which is the current scenario).

Thanks,
Ripu Daman

As I stated, "I assume the Voltages are identical otherwise forget it.

I also stated. "1066...review the JEDEC 800 CAS Timings & Voltage per CPU-z." If the DDR2 800 and 1066 @ 800 overlap {CAS & Voltage} then you 'should' be able to use them together. This requires you to boot with the 800 & 1066 separately and compare.

Good Luck!  

Hi,

I have put both rams together..but i haven't change any setting...its automatic only..can i change some setting if there is any or just be glad that it worked. My mother board is Asus P5Q pro.

Thanks,
Ripu Daman

Using the following as an example, use the highest CAS Timings of either set at the equivalent 'SPD'; in the case of DDR2 800 {400 MHz} look at the corresponding CAS Timings and Voltage of the DDR2 1066 {533 MHz}.

DDR2 800 4-4-4-12 @ 1.8v
DDR2 1066 5-5-5-15 @ 2.2v ; review the JEDEC 800 CAS Timings & Voltage per CPU-z
====================
DDR2 800 5-5-5-15 @ 2.0v ; and hope the Voltage disparity works

BIOS
DRAM Frequency -> 800 MHz
DRAM Timing Control -> Manual
CAS# Latency -> 5
DRAM RAS# to CAS# Delay -> 5
DRAM RAS# Precharge -> 5
DRAM RAS# Activate to Precharge Time -> 15
DRAM Voltage -> 2.0v

Hi,

The setting you suggested worked but I felt that my OS started reacting slower then before.... particularly for some applications like explorer, win-zip & few other applications & I did see much difference from 4 GB with 1066. Do let us know if I am wrong at some point & thanks for all the help.

Regards
Ripu Daman

IF you are ***ONLY*** running "DDR2 1066 5-5-5-15 @ 2.2v" by themselves and ***WITHOUT*** DDR2 800 4-4-4-12 @ 1.8v then change the settings.

ONLY DDR2 1066 5-5-5-15 @ 2.2v:

BIOS
DRAM Frequency -> 1066 MHz
DRAM Timing Control -> Manual
CAS# Latency -> 5
DRAM RAS# to CAS# Delay -> 5
DRAM RAS# Precharge -> 5
DRAM RAS# Activate to Precharge Time -> 15
DRAM Voltage -> 2.2v