FSB / GPU Relationship

[Titanion]

These are just some general questions that have been bugging me.

What effect, if any, will an overclocked fsb have on an overcloaked video card? I know it will increase the pci bus, but do you have to lower the gpu overclocked setting? Does the fsb affect the gpu at all? Do you need to set the video card back to default, overclock the cpu, then find a new setting for the gpu/ram, or will it still be the same?

I have also read about an increased fsb affecting RAID setups, even a mild overclock bringing the fsb up to 37.5
How dangerous is a pci bus of 37.5 for a RAID or other onboard devices?







<font color=red><b>To reign is worth ambition though in Hell:
Better to reign in Hell, than serve in Heav'n.</b></font color=red>
John Milton, <i>Paradise Lost</i>, II 262-263

 

[lhgpoobaa]

It depends on your motherboard.
IIRC all of the Amd via motherboards have their AGP/PCI speeds tied to the FSB by a multiplier/divider ratio.
So when you raise the FSB the PCI and AGP both go up, which can cauze all sorts of buggy behavior, particularly from the PCI devices.
AGP cards seem to be more tollerant, though even they have limits.

The Nforce1 and 2 dont however, as well as most intel boards. They have the PCI/AGP speed independent of the bus speed.

The OC settings of the acutal card remain the same as they are derived from a different clock... its just the transfer bus speed thats elivateed for the card.

Yes, even a PCI speed of 37.5 can be bad in the long term, but it depends alot of the device.
I had lots of problems at that speed with my overclocked KT133A chipset.

<font color=blue>Many modern games <b>must</b> be played multiplayer. And those you encounter online are, almost as a rule, <b>complete and utter cockmongers.</b></font color=blue> :frown:

 

[marneus]

card like the latest ATI ones do not like an overclocked AGP bus, newer bioses have a PCI/AGP lock so that they are always 33/66, no matter what you do with you system fsb...
Nforce2 & SiS746 both have this function I believe but not too sure which VIA chipsets have it...

Trust me I know what I'm doing... ooops, grab the cat... (Click me name to see me spec)

 

[phsstpok]

AGP speed has no direct relationship with video card overclocking speeds. That is, if you overclock your video card from 250/275 to 300/325 (my overclock for example), it doesn't matter if your AGP is at the default speed of 66 Mhz or overclocked to 80 Mhz. You will still be able to overclock your video card the same amount.

Think of the AGP speed as a communication speed. The computer and the video card can talk to each other a little faster when AGP is overclocked but neither the computer nor the video card themselves are running faster.

You will see a small improvement in performance when AGP is overclocked. This is not due to your video card being any faster but because the communication rate between them is a little higher.

The improvement is not large because the AGP bus is not saturated most of time.

<b>56K, slow and steady does not win the race on internet!</b><P ID="edit"><FONT SIZE=-1><EM>Edited by phsstpok on 06/06/03 01:56 PM.</EM></FONT></P>

 

[skligmund]

I currently have my FSB on my KG7-RAID set to 147 MHz (133 Stock), and my KT7E (which doesn't even 'support' 133 FSB) at 145 MHz. So from MY experiences, I would say that 37.5 is pretty safe.

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[phsstpok]

I forgot to answer your question.

How dangerous is a pci bus of 37.5 for a RAID or other onboard devices?

I don't know if 37.5 Mhz is safe. It depends on the mobo and your hard drives.

I have an Epox 8KTA3PRO (VIA KT133A). Usually I overclock FSB to 150 Mhz which puts my PCI bus at 37.5 Mhz. I've run into a modem a DVD-ROM that do not like this speed. My hard drive occasionally has problems. Sometimes it pauses or takes a long time to respond, not often but sometimes. No data corruption just noticible pauses. Doesn't happen when FSB is 145 Mhz.

AGP you can take very high without problems. Ask Crashman. I think he had a Radeon LE at over 100 Mhz AGP.

If you want to overclock but are worried about excessive AGP and PCI speeds then get a motherboard that can lock these speeds.

<b>56K, slow and steady does not win the race on internet!</b><P ID="edit"><FONT SIZE=-1><EM>Edited by phsstpok on 06/06/03 02:19 PM.</EM></FONT></P>

 

[Titanion]

Soyo kt333 dragon ultra

I have three 80 GB Maxtor Diamondmax HDDs (2 on a RAID)

I have sold my 1900+ and ordered a 2400+, and overclocking my fsb to 140 might suit my needs... 140*15 would get me 2.1 GHz

Do you think the stock cooler with the 2400+ can handle the jump from 133 to 140? How about 145?

145*15 would get me 2175

I wonder how much voltage I would have to add for that. Everything I read has suggestions for a 180 fsb, etc, nothing for small overclocks like 140 or 145?

<font color=red><b>To reign is worth ambition though in Hell:
Better to reign in Hell, than serve in Heav'n.</b></font color=red>
John Milton, <i>Paradise Lost</i>, II 262-263

 

[phsstpok]

have sold my 1900+ and ordered a 2400+, and overclocking my fsb to 140 might suit my needs... 140*15 would get me 2.1 GHz

You shouldn't have any problems with those bus speeds.

Do you think the stock cooler with the 2400+ can handle the jump from 133 to 140? How about 145?

I don't know how good stock coolers are. You can try it. However, I urge you to get an aftermarket HSF.

I wonder how much voltage I would have to add for that. Everything I read has suggestions for a 180 fsb, etc, nothing for small overclocks like 140 or 145?

It's not fsb speed that determines how much Vcore you need but how high you overclock the processor.

If you ran yours at 10 x 200 Mhz (not that you can with a KT333 mobo) instead of 15 * 133 Mhz it would still be at the stock 2000 Mhz. You'd just be running a faster bus. No Vcore increase would be necessary.

Now with small overclock like 15 x 140 or 15 x 145, you probably won't need much. 15 x 140 you can probably do with the default voltage. (What is that, 1.65 volt on an XP2400+?) Higher than that I'd guess that you would have to start increasing voltage.

<b>56K, slow and steady does not win the race on internet!</b>