I was wondering can i set ddr2-800mhz ram on my mobo MSI K8N Neo4 nforce-4? At the moment i have 1,5GB DDR1 400mhz RAM. the guy at the computer shop said that i cant upgrade ddr2 on my motherboard, but i see that people on the internet have dual core processors and dd2 ram on the same motherboard.
sorry for my englesh.

I happen to have that motherboard in one of my PCs and it is not compatible with DDR2 RAM. DDR2 is not backward compatible with DDR RAM. For one thing the notch is in a different position so you can't physically put in in the slot.

Ok, can i at least upgrade dual cpu on this motherboard? Do you have it on your msi motherboard?

What version of BIOS are you running, also what edition of the board do you have.

Unfortunately that is a socket 939, so your dual core CPU choices are going to be limited.

This is about Motherboard:

Motherboard ID 11/28/2005-MS-7125-6A61FM49C-00
Motherboard Name MSI K8N Neo4 Series (MS-7125)

Front Side Bus Properties
Bus Type AMD Hammer
Real Clock 200 MHz
Effective Clock 200 MHz
HyperTransport Clock 1000 MHz

Memory Bus Properties
Bus Type DDR SDRAM
Bus Width 64-bit
Real Clock 164 MHz (DDR)
Effective Clock 329 MHz
Bandwidth 2630 MB/s

Motherboard Physical Info
CPU Sockets/Slots 1 Socket 939
Expansion Slots 4 PCI, 1 PCI-E x1, 1 PCI-E x4, 1 PCI-E x16
RAM Slots 4 DDR DIMM
Integrated Devices Audio, Gigabit LAN
Form Factor ATX
Motherboard Size 240 mm x 300 mm
Motherboard Chipset nForce4(-Ultra)
Extra Features CoreCell, Dynamic Overclocking Technology

This is about my BIOS Version:

BIOS Type Award
Award BIOS Type Phoenix - AwardBIOS v6.00PG
Award BIOS Message W7125NMS V1.B 112805 09:34:44
System BIOS Date 11/28/05
Video BIOS Date 05/06/30

I have a single core processor, the FX-55. There were only a handful of socket 939 dual core CPUs that were supported by that motherboard and because it's so old your choices are limited as ATK SpAdE said.

For a list of the CPUs you board will support click Here

AMD's page about the CPU can be found Here

It would appear as if there are few choices you can buy if you want a Dual Core CPU.

However most big retailers (Newegg, TigerDirect) do not carry 939 X2 anymore. You would have the best luck on a resale site like ebay. I have noticed the average price to be about 80-100USD

It may be worth it to start saving up loose change for a newer MB/CPU/RAM combo because slowly the support and performance of anything 939 is going to drop.

tnx alot spade, but i think its best to buy new motherboard if i want to upgrade my pc. If i buy these one of these processors, they are maybe good today, but in a few months they will get old and i will have to buy new motherboard and everything. Its best to buy new motherboard now so i can upgrade it later. Thats probably what am i going to do.

I think that is a very wise choice, if you give us a budget I am sure we can put something togther if you need help choosing, if not, all the best.

I need to earn that money first, then i will see what am i going to do.