Question : Problem: Problems with DDR3 memory

Recently a put up a new system with motherboard

XFX nForce 790i Ultra SLI Motherboard - NVIDIA nForce 790i, Socket 775, ATX, Audio, PCI Express 2.0, SLI Ready, Dual Gigabit LAN, S/PDIF, USB 2.0, Firewire, eSATA, RAID

 Form Factor:        ATX
     
        Processor Interface:        Socket 775
     
        Processors Supported:        Intel Core 2 Duo, Intel Core 2 Quad, Intel Pentium Dual Core
     
        Additional Technologies:        3-Way SLI
     
        Front Side Bus:        1600MHz
     
        Northbridge:        NVIDIA nForce 790i SLI MCP
     
        Number of Slots:        4
     
        Number of Pins:        240-Pin
     
        Maximum Memory Supported:        8GB - 64bit
     
        Memory Supported:        Dual Channel Supported
              Single Channel Supported
              SLI-Ready
              2000MHz DDR3
              EPP 2.0 Support
     
        Channels:        8 Channels
     
        Audio Chipset:        High Definition Audio (HDA)
     
        Supported Devices:        2
     
        Hard Drive Types:        UDMA/33
              UDMA/100
              UDMA/66
     
        USB Version:        2.0
     
        USB Data Transfer Rates:        480Mbps
     
        LAN Type:        10/100/1000Mbps Gigabit
     
        Port Type:        2 x RJ-45
     
        PCI Slots:        2
     
        PCI Express X1 Slots:        2
     
        PCI Express X16 Slots:        1
              2 - (PCIe 2.0)
     
        PS/2 Keyboard Connectors:        1
     
        PS/2 Mouse Connectors:        1
     
        USB Ports:        10
     
        USB Rear Panel Ports:        6
     
        USB Onboard Headers:        2 - (expandable to 4 USB ports)
     
        FireWire Ports:        1 - 1394a
     
        LAN Ports:        2
     
        Audio Out Jacks:        2
     
        Line In Jacks:        1
     
        Microphone Jacks:        1
     
        Center Audio Jacks:        1
     
        Subwoofer Audio Out Jacks:        1
     
        IDE Headers:        1
     
        FDD Headers:        1
     
        Serial ATA Headers:        7
              1 - External
     
        ATX Power Connectors:        1 24-Pin Connector
     
        PC Power Connectors:        1 - 8 Pin
     
        Fan Connectors:        1 x CPU
              5 x Chassis
     
        S/PDIF Connectors:        1 - Coaxial, 1 - Optical

I was havimg problems installing windows vista ultimate 64bits on the system, I looked for help and it worked i only set up the voltage and timing that are specified in the memory specs. well so far so good, I was running with this

OCZ NVIDIA SLI-Ready Edition 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1800 (PC3 14400) Dual Channel Kit Desktop Memory

I installed vista with one stick(2GB) in slot 1 and then after success installation, I added up the second stick (2GB) in slot 3 after doing that I had a BSOD so I switched the sticks to slots 0 and 2, it worked great, everything was fine and smoothly until I (DUMB-STUPID) try to make a dual boot with WIN XP 64, I have some problems with the vista boot manager til I gave up, and decided to live the computer only running VISTA... I reinstalled vista to fix the MBR and using 4GB it did work till the final steps and then got BSOD saying IRQL not less or iqual... then I tried to reinstall only using 1 stick 2GB and it worked great but after installing drivers and everything again and putting the other 2GB back I got another BSOD saying crash dump memory
starting hard drive crash something, then I went back to only one stick and it works fine

what is it that I am doing wrong or messed up, I want to have the 4GB installed.
Thanx in advance hope you can help me
     

Answer : Problem: Problems with DDR3 memory

First with all 4gb installed reset bios defaults with the CLR_CMOS jumper(page 24 of the motherboards manual) after you save changes and exit and the system restarts re-enter the bios and change the memory to its advertised timings and voltage save and exit and see if you still get the BSOD, if so run Memtest(www.memtest.org) for atleast 4 loops. If it fails run it on 1 stick at a time.