What ram should i get ?? Asus crosshair V 990fx AMD 8150FX

If you have an FX 8150 then I assume you aren't a very light user so I suggest you get 8GB of RAM. A 2 module 8GB (2x4GB) kit would be the best option unless you want 16GB of RAM, either way you should use 4GB modules. 1600MHz modules have extremely close or identical prices to the 1333MHz modules so you might as well get the faster ones. Of course you should always buy name-brand modules from reputable manufacturers like G.Skill, Corsair, Kingston, or Patriot.

after a quick search on Newegg.com I found this kit:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

specs are: 2x4GB, 1600MHz, 9-9-9-24 timings (decent for 1600MHz) 1.5v
For only $29.99 this is a great deal, it's probably on sale and won't last long at that price.

why would you assume he's a "light" user? maybe he's a thrifty user....

http://www.newegg.com/Product/Product.aspx?Item=N82E168... <-- 8gb (2x4) on the QVL - 43.99

http://www.newegg.com/Product/Product.aspx?Item=N82E168... <--16gb (4x4) on the QVL - 79.99

btw blazothorn... the ones you suggested are not on the QVL so I wouldn't recommend them... though they would probably still work... better safe than sorry

cool thanx for the info....what about corsair ram are they any good ?? wich one would you suggest, i'm new to all of this, building my first build ever everything is being shipped to me as we speak, to tell you the truth i have no idea what i'm getting myself into, it will be fun i hope !! its even my first time in any forum of any kind lol !!

corsair is good... if you go to Asus.com, go to the support section lookup your motherboard and find the memory QVL it tells you what RAM has been tested and is known to work with the board... I would suggest getting 1600 mhz ram and verifying the ram is on the QVL.

I threw out the cheapest name brand kit with considerable specs. I find no fault with the kits you suggested, they are also well priced. I am a little more daring with my hardware (not that it's a good thing) and haven't had a problem that I couldn't solve. Although I did need to fight with my current set for a few days...

That's cool man and I understand, because i do the same thing with my system, but when someone asks for advice I try to go off documented sources because then they can't blame me for something not working..  

I think ill go with corsair vengence 16G 1600 Mhz i like the looks and the tall heat sink, i'm using corsair H80 cooler so they will most likely fit !! their on the QVL list too so i should be fine. 99$ so they are not so bad !! i think, i hope !!

supported corsair 1600 modules (just realized I still had the QVL opened)

CORSAIR HX3X12G1600C9(XMP) 12GB ( 6x 2GB ) DS - - 9-9-9-24 1.6 ● ●
CORSAIR CMZ16GX3M4A1600C9(XMP) 16GB ( 4x 4GB ) DS - - 9-9-9-24 1.5 ● ●
CORSAIR CMG4GX3M2A1600C6 4GB ( 2x 2GB ) DS - - 6-6-6-18 1.65 ● ●
CORSAIR CMD4GX3M2B1600C8 4GB( 2x 2GB ) DS - - 8-8-8-24 1.65 ●
CORSAIR CMG4GX3M2A1600C6 4GB( 2x 2GB ) DS - - 6-6-6-18 1.65 ●
CORSAIR CMX4GX3M2A1600C8(XMP) 4GB( 2x 2GB ) DS - - 8-8-8-24 1.65 ● ●
CORSAIR CMD4GX3M2A1600C8(XMP) 4GB(2 x 2GB) DS - - 8-8-8-24 1.65 ●
CORSAIR CMG4GX3M2A1600C7(XMP) 4GB(2 x 2GB) DS - - 7-7-7-20 1.65 ●
CORSAIR CMX4GX3M2A1600C9(XMP) 4GB(2 x 2GB) DS - - 9-9-9-24 1.65 ●
CORSAIR CMP6GX3M3A1600C8(XMP) 6GB ( 3x 2GB ) DS - - 8-8-8-24 1.65 ● ●
CORSAIR CMP6GX3M3A1600C8(XMP) 6GB ( 3x 2GB ) DS - - 8-8-8-24 1.65 ● ●
CORSAIR CMX6GX3M3C1600C7(XMP) 6GB ( 3x 2GB ) DS - - 7-8-7-20 1.65 ● ●
CORSAIR TR3X6G1600C8D(XMP) 6GB(3 x 2GB) DS - - 8-8-8-24 1.65 ●
CORSAIR CMP8GX3M2A1600C9(XMP) 8GB ( 2x 4GB ) DS - - 9-9-9-24 1.65 ●
CORSAIR CMZ8GX3M2A1600C8(XMP) 8GB ( 2x 4GB ) DS - - 8-8-8-24 1.5 ● ●
CORSAIR CMZ8GX3M2A1600C9(XMP) 8GB ( 2x 4GB ) DS - - 9-9-9-24 1.5 ● ●
CORSAIR CMX8GX3M4A1600C9(XMP) 8GB(4 x 2GB) DS - - 9-9-9-24 1.65 ●

1 dot means tested with 2 sticks two dots means tested with 4 sticks (ie if 2x4 works and has 2 dots the same kit with 4x4 will work)
http://www.newegg.com/Product/Product.aspx?Item=N82E168... <-- tested version of that ram... it's 84.99

I wouldn't spend $100 on 16GB of 1600MHz unless it was very low voltage (1.25v), allowing serious overclock room.