Best vidcard for OC'd AGP bus?

[AllDressedUp]

This may be a dumb question, but are most AGP video cards these days comfortable running at an AGP bus frequency of 83MHz?

If not, can anyone recommend some that would be?

Also, is there any type of rating on AGP cards that indicates what bus frequencies they support? For example, does it work like this?...

1x = 33Mhz
2x = 33mhz - 66Mhz
4x = 33mhz - 133Mhz

Or am I totally off base?

TIA.

 

[golfreak]

The question of running AGP cards at higher than their recommended 66mhz is not much of an issue any more after the BX chipset.
Most boards these days have a 1/2 divider which mean even at 150fsb, the AGP is only running at 75mhz.

As for running AGP cards at higher speed. I know the Geforce 2 GTS flies.
I'm running a GTS card on a BX board at 150fsb which means its running at 100mhz and I have no problems.
AS for other cards, I'm pretty sure they can run alot higher than the 66mhz but I am not positive.

 

[AllDressedUp]

Thanks, golfreak.

I'm planning to run this on an Iwill XP333 at a 166+ FSB, hence the 83MHz question.

If the card can't handle such a high bus frequency, would lowering it to 1x (41.5MHz?) solve the problem? (I really do not have a good grip on this stuff.)

 

[canadianpsycho]

1x would be 83 MHz.

 

[AllDressedUp]

So then the ratings work like this?...

1x AGP = 66MHz @ 133FSB (or 83MHz @ 166FSB)
2x AGP = 133MHZ @ 133FSB (or 166MHz @ 166FSB)
etc...?

If this is the case, is it safe to assume then that an AGP card that supports 2x or higher should have no problem running in 1x mode on an 83MHz AGP bus? Or are most cards designed to "lock in" only at specific frequencies like 66 & 133MHz, so you'd be running them out of spec at any other frequency?

 

[DClark]

The front side bus speed has nothing to do with AGPx1, x2, and x4.

The multipliers refer to the AGP port's throughput (the amount of data transferred on a 66mhz APG bus). A throughput of x1 is 266 MBps (megabytes per second), x2 is 533 MBps, and x4 gives you 1.07 GBps. In contrast, a PCI slot has a throughput of 133MBps.

Raising the front side bus will increase the bandwidth of the AGP port, but it's independant of the multiplier. Just think of it kind of like SDRAM (x1), DDR SDRAM (x2), and QDR SDRAM (x4) all running on the same fsb; they can all run on the same fsb, but the DDR and QDR ram theoretically can deliver 2 and 4 times more information respectively.

The actual fsb speed that the AGP port is running at is determined by the AGP divider in the bios, not by the AGP multiple. with a 133mhz fsb, the divider should be 1/2 (for 66mhz). On a 100mhz fsb the divider should be 2/3 (again to make 66mhz). If you had a BX board which did not officially support a 1/2 AGP divider, at 133mhz the AGP port would be running at 89mhz (133mhz x 2/3). You could still set the AGP port to x1 or x2 (BX boards don't support AGPx4); when set at AGPx2, the AGP port would have twice the throughput as at x1.

 

[sash1]

What DClark said is totally right. The AGP 1x, 2x, and 4x have absolutely, and utterly nothing to do with the speed it travels at, rather the rate of transfer the AGP bus has. The AGP bus is determined by the FSB of your processor (as is the PCI/IDE bus, but let's not get into that now...). The AGP bus runs at a speed of 66MHz. The AGP didviderm respectively is 2/3 (@ 100MHz) or 1/2 (@ 133MHz). All that AGP 1x, et-cetera controls is the rate of transfer:

1x : 266MB/sec
2x : 533MB/sec
4x : 1.066GB/sec

AGP 8x is under speculation and will allow 2GB/sec of throughput.

~Aunix

 

[AllDressedUp]

Thanks DClark & Aunix for the clarification. I think I'm starting to get it now.

What AGP card would you recommend for an AGP bus OC'd to around 83MHz? Matrox?

 

[DClark]

Most of today's graphics cards should run on an 83mhz AGP port speed, but I'd suggest that you spend a little extra for a name-brand card from a company known for quality PCBs (printed circuit board). Asus is a good manufacturer of GeForce2 and 3 cards, while on the Radeon front you may want to go with ATi over any third party manufacturers. I have a feeling that the initial batch of Radeon 8500s were all made by ATi, then distributed to the third party manufacturers though, as all the Radeon 8500 PCBs look the same.

One thing to note though is that you're also overclocking your PCI slots when running at a 124mhz fsb. I screwed up my old 56K modem from overclocking (though it was just a winmodem) to an unusual fsb, and my new cheap modem won't allow me to post on a 125mhz fsb (I use a 133mhz fsb so I'm only overclocking my P3 from 700mhz to 933mhz; my modem and graphics card are running at their stock PCI and AGP speeds); some cheap NIC cards and sound cards also have difficulty with overclocked PCI slots.

 

[AllDressedUp]

Sounds like good advice, DClark. Thanks.

And yep, I'm aware that the PCI bus'll be running around 41.5MHz as well. The only other card going into this system though is an inexpensive DVD decoder. So not really much at risk. I checked with the mfr. anyway, and they said go ahead and give it try.

Anybody else got any thoughts on this?

 

[Almighty1]

Hmm, while most of what is said is correct. What happens if you were running a BX Chipset with a 133Mhz CPU. There is no 1/2 Divider for AGP so 2/3 will be 89Mhz and not 66Mhz like everyone stated. Would this work okay with either the GF3 Ti500 or the Radeon 8500?

 

[DClark]

Actually, the last paragraph in my first post on this thread deals with the BX board not supporting a 133mhz fsb.

As for whether it would work for a GF3 or Radeon 8500, the only way to know is to try it. I find that I can't overclock my graphics card as far via powerstrip (core and memory clock) when I'm on an aggressive fsb, so it does stress the card. It will probably shorten the graphics card's life, but whether it shortens the life expectancy down to 3 years or 3 months would be unknown until it breaks.

Just remember that the golden rule of overclocking is "Don't overclock what you can't afford to replace."

 

[Dark4ng3l]

I know voodoo3's aculd run up to at least 100MHz+ agp busses....

 

[Almighty1]

<< Actually, the last paragraph in my first post on this thread deals with the BX board not supporting a 133mhz fsb.

As for whether it would work for a GF3 or Radeon 8500, the only way to know is to try it. I find that I can't overclock my graphics card as far via powerstrip (core and memory clock) when I'm on an aggressive fsb, so it does stress the card. It will probably shorten the graphics card's life, but whether it shortens the life expectancy down to 3 years or 3 months would be unknown until it breaks.

Just remember that the golden rule of overclocking is "Don't overclock what you can't afford to replace." >>



Interesting. Assuming that it was a BX with a 133FSB, would one need to tweak the core and memory clock to get it to stable or will it just work at 89Mhz AGP on it's own. I guess what I'm trying to ask is if the AGP speed is increased, does one need to change tweak the other clocks to a higher number?

 

[AllDressedUp]

FWIW, I ran into someone at a computer store that seemed to know what she was talking about and she suggested a board with 350 or greater RAMDAC for an OC'd AGP bus. Not sure why though. She also recommended a Voodoo card for its stability, Dark4ng3l. Hmm...

Matrox said they don't officially support an OC'd bus. But unofficially...

Anyway, it sounds like a Voodoo3 might be worth a try.

Thanks for all the input folks. If anyone has other ideas on the subject, I'm still open to suggestions.

 

[DClark]

In answer to Almighty's question:

I think it's just a pain in the butt to change clock speeds, so I don't really consider a card able to run on the fsb in question unless it can do so on its' stock clocking, but a card would generally be less stable at a higher AGP port speed with the same core and memory clock. That's not to say that it would be unstable though, as I've run my old Rage Fury Maxx on a 120mhz fsb (80mhz AGP speed) for hours with no problems on the stock clock (Maxxes aren't known for their AGP port stability).

I've read posts of other people being able to get cards to run on a 95mhz AGP bus, but you won't know if the card you get can do it until you try to post. The best thing to do would be to go to biased web forums and get people to brag about their highest AGP speed; Rage3D.com would be the place to ask about Radeons, while nVnews.net would be the place to ask about GeForces. Remember on the GeForce forum to get them to mention the brand name of their card as well.

Although I never owned a BX board (I went straight from an LX board to an Apollo Pro 133A), to my knowledge some BX boards also lack the 1/4 PCI to FSB divider; that means a board without that feature would also be trying to run the PCI slots at 45mhz (up from 33mhz). A BX board with the 1/4 PCI divider (Abit's BX 133-RAID would be a good example) would probably be able to overclock further, as the PCI cards would be running closer to spec.

 

[Almighty1]

<< In answer to Almighty's question:

I think it's just a pain in the butt to change clock speeds, so I don't really consider a card able to run on the fsb in question unless it can do so on its' stock clocking, but a card would generally be less stable at a higher AGP port speed with the same core and memory clock. That's not to say that it would be unstable though, as I've run my old Rage Fury Maxx on a 120mhz fsb (80mhz AGP speed) for hours with no problems on the stock clock (Maxxes aren't known for their AGP port stability).

I've read posts of other people being able to get cards to run on a 95mhz AGP bus, but you won't know if the card you get can do it until you try to post. The best thing to do would be to go to biased web forums and get people to brag about their highest AGP speed; Rage3D.com would be the place to ask about Radeons, while nVnews.net would be the place to ask about GeForces. Remember on the GeForce forum to get them to mention the brand name of their card as well.

Although I never owned a BX board (I went straight from an LX board to an Apollo Pro 133A), to my knowledge some BX boards also lack the 1/4 PCI to FSB divider; that means a board without that feature would also be trying to run the PCI slots at 45mhz (up from 33mhz). A BX board with the 1/4 PCI divider (Abit's BX 133-RAID would be a good example) would probably be able to overclock further, as the PCI cards would be running closer to spec. >>



Cool..... it seems like it's hard to find people who are using a BX with a OC bus for some reason. I'm using a ABIT BE6II v2.0 which is just the slot 1 version of the BX-133. It uses the same BIOS and the only difference is with the Slot1 to FCPGA converter, I can manually control the voltages with jumpers. It does have the 1/4 PCI Divider. It's just missing the 1/2 AGP Divider. 1/1 and 2/3 are the only choices.

 

[golfreak]

From my experience with BX boards.
I have been able to run Voodoo3 cards to 100mhz(thats running at 150fsb)
I was running my G2 GTS card at 142fsb(thats 95mhz AGP speed)
Right now, I'm running my R8500 at 140fsb.

 

[Marine]

I don't have any BX boards anymore, however, I have several CUSL-2C boards with 815E chipsets. I cannot find a GeForce 3 card that will run faster than default FSB on this chipset. I have tried Gainward CardExpert cards, and cards from several other manufacturers, but to make the cards support D3D, always have to declock back to default FSB, which defeats the purpose of building performance PCs. About to pull out my hair, have used all the available BIOSs, still no joy. Anyone have any luck in O/Cing a GeForce3 card on the 815E chipset? BTW, my boards are all ASUS.

 

[AllDressedUp]

FWIW, I tried a Voodoo3 3000 on my Iwill XP333-R, and it seemed to heat up quite a bit. So I put back an old Diamond PCI card instead and it went up to about 165FSB without much difficulty.

I'm not sure if OCing caused the Voodoo to heat up or not. I suppose it could simply not have been receiving enough power. Or perhaps it wasn't installed correctly. I'm not very well-versed on AGP stuff. It took alot longer to boot up as well though, so for now it's gathering dust.

 

[oldfart]

Voodoo3 cards run hot as a mother. Its normal.

 

[AllDressedUp]

Thanks old fart. I'm surprised that's normal, but this really is new territory for me.

 

[HappyGamer2]

i have a bx440 board, i overclock my system with a software overclocker. I can't change the agp divider when overclocking. results: voodoo5 can handle a 133 fsb, radeon can't , the highest radeon will go is 124 fsb

 

[golfreak]

Don't know what kind of Radeon you are using but I'm running a Radeon 8500(I have both OEM and retail) and its 100% stable at 140fsb on a BX board(a Soyo 6ba+ III to be exact). That would running at 93mhz AGP speed.