a q9550 at 3.8 ghz will not bottleneck that bad even with a gtx 580 the q9550 is a beast of a cpu even know.

but the big problem with the q9550 that it hasn't L3 cache and most of the new games require L3 cache to run at high fps .

SKYSTAR i dont know where you are getting all of your info but i don't find it very helpful the q9550 is still a very fast cpu for most every thing you do except for a couple of games maybe and L3 cache doesn't make that big of a difference. Please make sure that you post accurate info to help the OP.

In most games the Q9550 at 4.0 Ghz is almost on par with the i7 920 at 4.0 Ghz there are exceptions

klepto12 :
the q9550 is like the amd athlon II x4 645 it is a quad core cpu without L3 cache ,in many games the phenom II x2 (dual core cpu) will beat the amd athlon II x4 due to it's L3 cache
see the huge role of L3 cache in duke nukem review here
http://www.techspot.com/review/411-duke-nukem-forever-performance/page6.html
and in deus ex here :
http://www.techspot.com/review/436-deus-ex-human-revolution-performance-test/page7.html
and did you ask your self why your cpu (i5 2500k sandy bridge ) has only L3 cache ???????????
the answer : because the sandy bridge series is especially for extreme gaming and extreme gaming require L3 cache not L2

Ok Ask the techspot crew and see who is right? also the q9550 has 12mb of L2 cache not 512k like the cpu you posted and is on par with the i7 920 look up the benchmarks and see for yourself DNF was a crappy game and very few games are L3 dependent so your remark is mute.

it has 2 mb L2 cache not 512 kb + higher clock speed and 4,00 ghz fsp

weather you say that or not your wrong the q9550 is far better and matches the i7 920 at 4.0 ghz in most games

http://forums.vr-zone.com/news-around-the-web/533738-core-i7-860-4-0ghz-vs-q9550-4-0ghz-43-benchmarks-single-ati-5850-1ghz.html

first : this is i7 860 not i7 920 as you told me
second :see this review on techspot ,this review contains both of q6600 (2.4ghz ,8mb l2 cache , a Little slower than q9550 ) and amd athlon II x4 620 ( 2.6 ghz ,2mb L2 cache , a Little slower than than x645)
http://www.techspot.com/review/197-amd-athlon2-x4-620/page7.html

the i7 860 is faster than the i7 920 anyway so point is still there the q9550 is a lot faster than the q6600 dont know what you mean but alas im done arguing either way the q9550 is still faster and can be overclocked to 4.0ghz.

anyway the q9550 has the same performance of i7 860 in some games not all and that happened because there is many games depend on L3 cache

SKYSTAR u said that L3 cache gives higher fps. But the fact is L2 cache is much much more faster than L3 cache. So theoritically Q9550 with huge 12MB L2 cache should give more fps than L3. But there r other things that should come in concidaration like, i3, i5, i7 processors access ram directly and use QPI Path but the Quad cores don't thus make them faster.
As far as i know an Q9550 @ 4.0GHz is almost equevalant to i7 965 @ stock. But Sandy Bridge I7 r much more faster @ gaming as they have integrated Graphics. I just know these things from other foroums. I don't know exactly as i don't have any of these CPUs. Make me correct if i'm wrong.

Good roundup of benchmarks. This is exactly why I held onto my Q6600 at 3Ghz with 5850 for so long as the first generation i7/5 processors didn't offer enough of a performance increase for what I used the machine for. I held off for Sandy Bridge and am glad I did. For 1680X1050 I would say that you won't have much or any of a bottleneck with 1 card. I'd get one card and then see what you think, 2 cards would most likely require a PSU upgrade as well unless you had the foresight to buy a high power unit to support future upgrades. Buying 2 cards and a PSU is quite an large purchase and could be disappointing if the CPU does present a bottleneck (which I think from memory it would do, at least slightly).

thanks again SKYSTAR & many thanks 2 Arris

this makes me laugh

the truth should make you burst in tears