ok heres the Question whats the difference between them numbers?

DDR2 800,667,533

and whats best for a gaming PC?

Afaik, that number refers to the FSB clock speed. In that case, higher should be faster, but you have to make sure your mainboard can handle the speeds. Wouldn't make sense to buy RAM clocked at 800MHz when your mobo can only use 667MHz.

Also depends on the CPU. There's no point using an 800FSB mobo and RAM if your CPU's FSB is running lower.

Find what FSB your CPU and Mobo use, and get the RAM that's the lower of the two.

Quote from Dooonster :

ok heres the Question whats the difference between them numbers?

DDR2 800,667,533

About 133.

Sorry, couldn't resist.

The RAM speed best for you is whatever is double the FSB of your motherboard. If your FSB is 333, the equivalent speed DDR2 RAM is 667. But you can still use 800 on any recent mobo afaik, you just change the strap in the BIOS. Whatever that is, I haven't got a modern rig yet, I've just been doing a lot of research lately.

the mother board will be a new nvidia one N680i and supports the 3 numbers i told you

heres the spec (im in china so sorry for the Chinese writing)

型号 C.N680i SLI 九段玩家版
适用类型 台式机
主板架构 ATX
CPU插槽类型 LGA 775
支持CPU类型 支持Prescott,Pentium D,Celeron D,Conroe系列处理器
前端总线频率 支持533MHz,800MHz,1066MHz,1333MHz前端总线
北桥芯片 nVIDIA nForce 680i SLI
南桥芯片 NF 590 SLi
支持内存类型 DDR2
是否支持双通道 支持
内存插槽数量 4 DDR2 DIMM,支持双通道DDR2 800,667,533
板载声卡 板载Realtek ALC885芯片8声道HD声卡
板载网卡 板载两颗Marvell 88E1116网络芯片支持双千兆网络
七彩虹 C.N680i SLI 九段玩家版 扩展参数 我要挑错
硬盘接口 ATA 100,ATA 133,S-ATA150,S-ATA II
磁盘阵列类型 SATA
磁盘阵列模式 RAID 0,RAID 0+1,RAID 1,RAID 5,RAID JBOD
支持显卡标准 PCI Express SLI
PCI Express插槽 3×PCI Express X16,2×PCI Express X1,中间蓝色PCI-E插槽为物理加速插槽，仅支持8×传速带宽
PCI插槽 2×PCI
扩展接口 10*USB2.0,2*1394a
七彩虹 C.N680i SLI 九段玩家版 其它参数 我要挑错
电源回路 6相电路
电源接口 24PIN+8PIN电源接口
特色功能描述 SLI技术
其它性能 热管＋风扇散热

cpu will be a E6850 @ 3.0ghz dual core
LGA 775 0.065um L2 4096k 1333mhz

heres the spec again

Intel Core 2 Duo E6850 主要参数 我要挑错
型号 Core 2 Duo E6850
适用类型 台式机
接口类型 LGA 775
核心类型 Conroe
生产工艺 0.065um
核心电压 1.3V
主频 3.0GHz
外频 外频 333MHz
倍频 9X
一级缓存 L1 128K
二级缓存 L2 4096K
前端总线频率 1333MHz
Hyper-Threading(超线程) 不支持 Hyper-Threading(超线程)
Intel Core 2 Duo E6850 功能参数 我要挑错
64位处理器 是
核心数量 双核
Virtualization(虚拟化) 支持
Intel Core 2 Duo E6850 其它参数 我要挑错
其它性能 TDP为65W/支持MMX/SSE/SSE2/SSE3/EM64T指令集/支持提供硬件保护功能的LT技术

now im just tossing between the best memory to buy

http://www.newegg.com/Product/ ... aspx?Item=N82E16820145034

That's one option.

i cant get that here

i can get this tho

http://product.pconline.com.cn/memory/corsair/198057.html

also for running all of this including the 2 8800gt's what power should i need 1 600w or a 450w?.
It also has some Uv lights in the case and water cooling and a couple of fans on the HDDs and 4 hdds 1 blue ray player 1 DVD ram and a DVD rom independent sound card and 2 cooling controllers,

think thats it lol

Well, you didn't look hard enough. It was actually advertised on the page that you linked above

http://product.pconline.com.cn/memory/corsair/161086.html

The memory you are looking at is, in my opinion, overkill. The stuff above is fine for your needs.

As for the power supply, definitely get the 600W, lol. 450 is most certainly not enough to run two graphics cards AND all your peripherals. Take a look at the Corsair 620HX if you can get that there...

its advertised but with no price

i can get a tt toughpower 650 w its cheaper and its probably better in some ways with support for 4 sli cards all plugging into it so think i will go for that.

Thanks for all the help guys much appreciated

the ram you can get will be good for you. and i would pick up the toughpower 650w if you can get it. just to let you guys know ddr1066 ram will work with a board that only supports ddr533, ddr667, ddr800. it will just run at a lower clock speed until you either overclock it or adjust the memory strap in the bios but have the memory running higher than your fsb on your cpu doesnt benefit much. so run lower clock speed and tight timings if you wont be overclocking. ddr800 with 4-4-4-12 timings will run about the same performance as ddr1066 at 5-5-5-15 timings.