• Welcome to Overclockers Forums! Join us to reply in threads, receive reduced ads, and to customize your site experience!

AGP or PCI video cards in an overclocked system?

Overclockers is supported by our readers. When you click a link to make a purchase, we may earn a commission. Learn More.

Posy Rorer

Mar 21, 2002
I'm looking for recommendations for a video card, under special circumstances.
I have an Asus P2B mainboard and a Celeron 400mHz CPU (SEPP,Slot
1), which I plan to overclock at 133mHz FSB. Keeping that in mind, I understand there are problems overclocking an AGP video card over 66mHz bus speed,
because the AGP spec is not rated for speeds above 66mHz. My question
is this: will my computer system be faster overall with a PCI card running at 133mhz bus frequency, or an AGP card running at a slower bus freq. of 66mHz?

The options I had in mind for an AGP video card is an ATI Rage 2C (w/ 4mb memory. I can get it for a good deal, but is anything less than 8mb unacceptable?), or an ATI Xpert@Play 8mb. For a PCI card, I can get a
Matrox Millenium. Any recommendations or things to avoid? I'm
looking for quick video speed browsing the Internet and with wp/office
Welcome to the Forums!!!

onto the questions at hand...

the pci bus speed spec is 33 mhz, not synchronous with the bus speed of the system (so not 133)...typically there are 'dividers' associated with the fsb of a system to give the pci bus and agp bus their appropriate speeds of 33/66 respectively. For example with a bus speed of 100 mhz, the dividers are 1/3 for the pci clock and 2/3 for the agp clock..or a ratio of 3:2:1 for pci, agp and system respectively.

Now on most NEWER motherboards, there are more dividers to allow the user to change fsb speeds..meaning you can go up to 133 mhz for the FSB but then new dividers kick in and its 1/4 for the pci bus speed and 1/2 for the agp bus speed giving you a ratio of 4:2:1 for pci, agp, system respectively.

First thing to do is find out if your motherboard officially supports a system bus speed of 133 mhz...if it does then it will also have dividers for that speed and your pci and agp bus's will both be running in spec and it wont matter whatever card you use...

if it does not however and you run your system bus at 133 mhz, then your pci clock will be running at 44.33 mhz, not 33 and your agp clock will be running at 88, not 66...dangerously out of spec for both devices, which means youll have to get some damn good quality and expensive devices that would support a higher bus frequency.

regarding the speed of the video card, the bus speed for an 8 or 16mb budget or legacy video card will have no bearing on the performance of the card...you would not ever see any bottleneck issues with anything up to 8mbs...when you start going a little more though, or have a newer graphics card that has a faster gpu and faster memory...then you need a faster bus speed to accomodate that...so between an agp or pci 3d card, the faster option would ALWAYS be the agp card but in some cases it doesnt make a difference because there is no bottleneck with the old 3d pci cards

as far as the graphics card you are going to use...my 2nd computer i bought had an ati rage iic card with 8mb of video memory..it was fine for 2d applications but nothing beyond that..so if you only have the 4mb version dont even think about playing games or doing anything remotely close to photo or video editing...otherwise youll need at least an 8mb card but nowadays 16 is a little more preferrable.

any more questions?

Last edited:
oh by the way..you said you were getting a good deal on the graphics card...i hope you arent paying anything more than $10 or $15 for it...right?

I've been overclocking a lot of 440BX motherboards recently and they only have a 2/3rd divider. I've run a Radeon 8500 at 83-100 mhz and so far haven't had any problems (2-3 weeks), but I notice the ram chips get real hot to the touch. But everything is totally stable in 3D. Haven't be able to get over 150 FSB on any of my CPUs though.
ucfswimmer said:
oh by the way..you said you were getting a good deal on the graphics card...i hope you arent paying anything more than $10 or $15 for it...right?


Well thanks for the very informative and detailed message Jeff. I can see now that I wasn't paying much attention to what I'd read about how the PCI (and AGP) peripherals need to remain near their standard 33/66 bus speed specs, regardless of the FSB speed. Apparently, my Asus P2B (rev. 1.10) is only listed as a 100mHz FSB max. board, but can "unofficially" do 133mHz bus. However, I'm hearing that my Mendocino Celeron 400 is not good enough to run on a 133mHz FSB. If that's the case, I can only overclock the Celeron to 100mHz FSB, and thus will probably have no problem getting the right dividers set for the PCI/AGP standard spec. The deal on the ATI Rage 2C 4mb graphics card is $15 (that's $15 CDN, or about $10 US). But I'd go up to $30 for a used video card, and for that I can get a Matrox G200 8mb, a Matrox Millenium PCI, an ATI Xpert@Play 8mb or a Diamond Voodoo 3 16mb. Any cards like these that are particularly fast for 2D stuff like web browsing/wp/general apps or at least stable under slightly higher bus speeds than the std. spec?
I'm not heavily into games, but I want to see windows popping up as fast as I can blink!
Jeff, you're awesome

I never knew what dividers were before reading your article.

Very clear and readable
well thank you...all ive mentioned ive learned from reading what others have posted here on the oc.com forums...so maybe one day youll pass on what you read from me :D

as far as OC'ing the mendocino...yea 133 is a little too much to dream for...i just got a celeron 800 to 133 but it was a long and ardous journey ;-) unfortunately the mendocinos are not quite as easy to just go right for 133...im not familar with the mobo you mentioned but if you look around sometimes you can find mobos that will support a 100/112/124/133 FSB in which case you could try running it at 112 or 124 (they come in all varieties and increments..just giving you an example)

and as for the video card...well if youre willing to go up to at least $25-$30 then check this out

i actually have the same graphics card in one of my systems now and ive had good luck overclocking the card itself...2d is no problem and if you ever wanted you could even run 3d games on it too if you were so inclined...always good to leave yourself a little room to breathe...

im glad i could finally help someone out..if you have any other questions then shoot and ill try and answer them.

If you check your mobo you'll find jumpers for 103. 105.110,112 and a few more. The P2B is an excellent board as is the 440BX a classic chipset. Experiment with your jumpers. You'll be surprised what that board will let you do. Be sure to turn sideband addressing off. This will allow you to push the agp bus a little harder. Don't be surprised if you have problems with the high FSbs. The 400 Celly has a high multiplier ( 6.0 ) and questionable L2 cache speed. You may get higher by turning L2 off. Look for some of the older overclock info on the front page. Overclockers.com helped pioneer locked multiplier overclocking and Joe has some good info there. You can also check the CPU database and see what guys were getting back there. Good luck.