Would i be able to put a high-end card in my computer?

[Emperor Charlemagne XII]

IO have an ANTEC 900 TWO CASE
1TB HDD
GTS 250
i7-930
6gb ram
i dont know the motherboard but it used to have 12gb or ram but the motherboard couldnt handle it so it we went to 6gb
i dont know the powersupply but i would be able to change it so it doesnt matter
would i be able to put a 6990, 6970,6950 , 6870

or nvidia 590, 580 ,570 ,560 i want a strong gpu that would last on ultra for a considerable time ...

[Knight of Heaven]

Hum with out knowing the motherboard, i think no one can help you, but in theory you could put those graphic cards...but only knowing the motherboard, one can be sure.

btw, i dont understand, you had 12gb ram instaled on your motherboard before? how come she didnt handle it??? you mean the CPU didnt handle that much Ram more likely, few CPUs can 12GB unless you have high end CPUs becouse for motherboard is irrelevant how manny RAm you put there, given that you have enough slots. Also the power supply maybe didnt bring much juice. It depends realy, only seeing my friend.
But you have an i7 the cpu should cope with 12gb...hum that is strange.

Anyway
What i can tell you is any of those cards would do fine, in theory, but no assurances. Il sugest Nvidia though.

[Top-Tier-Tech]

Hum with out knowing the motherboard, i think no one can help you, but in theory you could put those graphic cards...but only knowing the motherboard, one can be sure.

btw, i dont understand, you had 12gb ram instaled on your motherboard before? how come she didnt handle it??? you mean the CPU didnt handle that much Ram more likely, few CPUs can 12GB unless you have high end CPUs becouse for motherboard is irrelevant how manny RAm you put there, given that you have enough slots. Also the power supply maybe didnt bring much juice. It depends realy, only seeing my friend.
But you have an i7 the cpu should cope with 12gb...hum that is strange.

Anyway
What i can tell you is any of those cards would do fine, in theory, but no assurances. Il sugest Nvidia though.

Just for the record this guy has extremely limited knowledge of computers.

@OP:

You motherboard will definitely support any of the cards you listed, it is important that you find out what your PSU is so that we know if you need to upgrade it or not, depending on the GPU you choose you may need up to a 600 watt PSU. Any LGA1366 motherboard (what you have) can support 12GB of RAM although your system typically won't use more than 6GB ever anyway. It sounds like you had some bad RAM or a BIOS issue.