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Thread ID: 41686 2004-01-19 08:01:00 F.S.B. and graphic boards BobM (1138) Press F1
Post ID Timestamp Content User
208472 2004-01-19 08:01:00 With all other specs. in my P.C. well over what is required to play games does the F.S.B. of the MOB make a difference to the graphic cards performance. ??. What I am really asking is if my mother board has a F.S.B of 266, is it worth buying a graphics board which is capable of using 400 BobM (1138)
208473 2004-01-19 08:54:00 simply put, graphics cards don't use the fsb. the fsb is more to do with data in and out of the cpu. tweak'e (174)
208474 2004-01-19 09:15:00 tweak'e

Are you sure you are right here? As far as I know the only two buses coming out of the CPU are the FSB and the BSB (back side bus to the cache).

Have a look at:

www.tomshardware.com

BSB not shown in this diagram
JohnD (509)
208475 2004-01-19 09:48:00 bsb is not really used much these days (i assume your meaning the bus to the l2 cache on the motherboard or slot board)

if you look in that first diagram at tomshardware you will see the fsb or system bus is the only thing coming out of the cpu. the viseo cards connect via the agp bus. changeing fsb speeds dosn't change the agp or video card speeds.
tweak'e (174)
208476 2004-01-19 10:09:00 > simply put, graphics cards don't use the fsb. the fsb is more to do with data in and out of the cpu

OK - changing the FSB doesn't change the AGP speed but AGP still has to get back to the CPU via the FSB - so I guess the above statement isn't quite true?
JohnD (509)
208477 2004-01-19 10:33:00 true the agp still has to get back to the cpu via the fsb, hence the "simply put". the fsb can limit the speed of the whole pc. buying a fast video card for a slow pc (weather the pc is slow due to fsb or other is irelavent) is a bit pointless. tweak'e (174)
208478 2004-01-19 20:27:00 Bear with me guys, firstly I am told that the fsb speed is irrelavent, now I'm told its crucial.?? BobM (1138)
208479 2004-01-19 21:12:00 The FSB is divided down by the AGP controller chip to a speed of 66mhz whether the FSB is 133/266/400. So the AGP card only ever runs at 66mhz anyway on all systems in normal modes.

If you overclock the FSB (to say 430mhz) then the AGP controller still divides the speed the same way so the AGP card will then run at 70-80mhz. New motherboards allow you to lock the AGP speed while overclocking the FSB.

AGP by the way uses the PCI bus (which is 33mhz standard) and multipies it by 2 getting the 66mhz.

So the graphics card while working with dividers on the FSB is locked into using 66mhz (or higher if you overclock the FSB with a natural limit around 80 odd mhz at which the cards usually start to produce errors.)

Changing the vidcard may improve performance if the CPU has spare power still available but ultimately its the CPU speed will limit it. Going to a motherboard with a faster FSB will help performance but not because the cards running faster but because the CPU and busses for it can perform more calculations quicker giving an effective speed boost to performance overall including the framerate in the game.

Hope that helps understand it.
John Grieve (367)
208480 2004-01-19 22:26:00 > if my mother board has a F.S.B of 266, is it worth buying a graphics board which is capable of using 400

> With all other specs. in my P.C. well over what is required to play games

if your pc is well over the specs required and the gamesplay fine and at a good quality and res they is no point in upgradeing your video card.

the FSB dosn't determin the speed of the graphics card. the only thing to really clog the video card is the agp which even at 4x should be fine even with the top end cards. however its not much point buying top end video card if your cpu/ram etc won't let the game run fast enough.

you might get better help if you post what sort of pc/cpu/ram/video card you have and the games you play on it.
tweak'e (174)
208481 2004-01-22 10:07:00 Thanks John and Tweak'e. The paragraph < Going to a motherboard with a faster FSB will help performance but not because the cards running faster but because the CPU and busses for it can perform more calculations quicker giving an effective speed boost to performance overall including the framerate in the game.> says it all as far as my query is concerned however I would like to be given an educated guess as to what board would be optimum price wise for my system as my gaming results are abysmal at the moment with Halo. AMD Athlon 1.9+ 768ddr ram 40gb 7200 hd FX 5200 graphic card BobM (1138)
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