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PIII 733 only runs@550 on Asus BX board!

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Last response: in Motherboards
November 27, 2000 8:48:31 PM

Please help me because I have to underclock my PIII to 550! I bought this PIII 733 to put in my Asus P3B-F. I have an Nvidia GeForce card, SB Live!, and PC133 sdram. It runs fine under Windows 98 and 2000 and in all my apps, but once I run Counter-Strike (about the only game I play) for 15-30 mins it locks up on me. I thought the BX133 platform was supposed to be an excellent platform! I did my homework before doing this, why is it only locking up in games? What am I doing wrong here?

More about : piii 733 runs 550 asus board

a b V Motherboard
a b Ĉ ASUS
November 27, 2000 11:00:12 PM

open up your manual to page 17. set your #6 dipswitch to [OFF], as indicated, for 2/3 times FSB to give your AGP channel the appropriate frequency (133MHz times 2/3 = 88MHz). turn the page. You have purchased an EB chip. EB chips rely on an FSB of 133, times an internal multiplier (5.5x in your case), to achieve nominal speed (733MHz, inyour case) Therefore, you must set your cpu external frequency to the setting indicated for CPU/DRAM 133.0MHz, and PCI 33.4MHz (#6thru10 [OFF]). Look on the next page for CPU core settings. Look on the next page. Set the CPU core:BUS frequency multiplier to the 5.5 setting (again, 5.5 times 133 = 733). That's 1 thru 3 OFF, and #4 ON.

Now Boot. If this doesn't work, I'd be surprised. But it may not. BX is a 100MHz FSB chipset by design. The fact that it is stable at higher settings is a testiment to the broad tolerances built in to the BX design. But, THE REASON that your EB chip is not appropriately recognized in the 'jumper free' mode as a 733MHz chip is that BX wasn't designed to recognize EB chips. Therefore, it just lands on the default CPU frequency of 550MHz.

The real beauty of the BX chipset is that it can take advantage of the TALLER internal multipliers of the E chips. My 700E, for example, has a 7x internal multiplier. If I feed it 100MHz on the FSB, it goes 700MHz. If I feed it 133MHz, it is forced to run (or fails to run) at 933MHz (7x133=933). It is that simple. I was lucky, in that my 700E chip actually tolerates 140MHz x 7x = 980MHz !!!!! Even more cool is that the AGP channel runs at 93MHz at this setting, so my GeForce is really performing at 40% faster than I paid for !!!!

This is because, as Tom P. has described, the absence of a 'divide by 2' setting in BX for the AGP channel forces us to attempt to use multiply by 2/3X (1X is clearly too fast !). As a result, BX makes 133MHz X 2/3 = 88 MHz. At 140, well, do the math!!! You've got the GeForce, so 88MHz shouldn't be a problem.

One consequence of your choice of the 'EB' chip is that you will have to push your system over '133' FSB to get faster CPU speed. Ya shoulda' got an 'E' chip, because if you couldn't make it to 133MHz, at least you could make it to 120, or 115, forcing your CPU to go faster than its rated speed.

I hope this helps you understand the BX settings as it relates to the E versus EB PIII coppermines.

Good luck.

Clonan, er, the Cyberian
a b V Motherboard
a b Ĉ ASUS
November 27, 2000 11:16:00 PM

Clonan here, again. Aside from the fact that you got the EB chip (I almost did the same thing), it seems like you made the right decisions. BX wasn't designed for 133, But...If the 133 settings I described don't work, just try a setting slightly lower. On page 18 of your manual, see the alternatives ? Try 124 MHz CPU, 31MHz PCI. At least this will allow you to overclock your GeForce to 82MHz, and your CPU will be at about 700MHz. Well, it's better than 550 anyway.
Again, good luck.
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a b V Motherboard
a b Ĉ ASUS
November 27, 2000 11:22:36 PM

one more thing.... don't forget to disable jumperfree mode (page 20) ! jumper setting 1-2
November 28, 2000 7:55:41 PM

My motherboard has the CPU softmenu setup so I was able to make all of those settings in the bios without using jumpers. AGP can't be changed from 2/3 but I set FSB to 133 with a 1/4 PCI divider. I have the multiplier settings running fine because my computer runs fine at 733 (used cpu id). Everything works on the computer at 733 except for when I play Counterstrike, and probably any other games which leads me to believe it has something to do with the video card. I can play for about 30 min or so before it locks up, but that's it.

If you know what could be causing this I would truly appreciate any help you could give me.
a b V Motherboard
a b Ĉ ASUS
November 28, 2000 8:15:12 PM

If you have multiple devices, like Sound card and video card, using the same IRQ, then the game may try to access both at the same time and crash the computer. If you're in Win2K you can right click on your "My Computer" icon and then go to Hardware settings (or something, I can't remember right now) then select Device Settings and View by Resources and see how many devices use the same IRQ. Mainly, you don't want the Vid. Card, Sound Card and (oddly enough) Hard Drive controller to use the same IRQ. The Vid. Card and Sound Card are the biggies though, IMO. Poor me, on my A7V I have about 6 devices using IRQ 9! (NIC, Modem, Vid Card, Sound Card, ATA Controllers, USB, and something else...) Oh the woh!

November 28, 2000 8:28:49 PM

That would be a valid point if I always had problems with my system when running games, but it only has problems when I run it at 733 which has forced me to underclock it to 550.
a b V Motherboard
November 28, 2000 9:37:11 PM

Sounds like your graphics chip is overheating. Try using a 486 fan on your graphics chip if there is not a fan on the heatsink (the case with some Geforce2 MX cards). If you have a fan on it and it still is overheating, try using a self-adhesive CPU cooler on your Video chip instead of the stock cooler. Both of these solutions require you to leave an empty slot below the AGP slot for room!
a b V Motherboard
a b Ĉ ASUS
November 29, 2000 8:51:13 AM

Have the smae problem with a 650mhz 100Mhz BX board. Counter-strike... but also other games
Whats the max Watt of your power supply?
How does it lock up, can you describe?

P3 650 n.oc. /GB BA6 BX Chipset/ Viper V770 Tnt2/ 3x64MB 100/133Mhz RAM
a b V Motherboard
a b Ĉ ASUS
November 29, 2000 9:14:03 AM

My brother also wants to upgrade to a 700MHz+ processor on his board, what type should he buy? He is running a 350MHz now...
We haven´t found the revision number on his mobo yet, this was also an important factor right? it should be some rivision number and later versions.
What frequencies will the board run at? i think he has PC100 memory on it, so that won´t go 133MHz if he´s unlucky..
a b V Motherboard
a b Ĉ ASUS
November 29, 2000 8:16:33 PM

Try to put some termal-grease under the green heat-sink on the chipset. Before I did that, mine would simply reset after 20-30 min of URT, when running at 7x124MHz. 7x112MHz never crashed.

My sys: PIII 700E, Abit BH6, GeForce2, SbLive, 128M PC133....

Hope It helps you.

When your windows breaks down remember:
Linux is still here :smile: .....
a b V Motherboard
a b Ĉ ASUS
November 29, 2000 11:43:51 PM

Hi BlackLoTuS

I have a PIII 733 running stable @ 150fsb (825Mhz) in my ASUS Cubx motherboard. I removed the green heat sink from the Intel AGPset and replaced it with a Lasagna BGA Cooler Type A,(perfect fit) which I purchased at I have the motherboard set to jumper free mode.
My system:
8 Gig WD HD
PIII 733(@825 Mhz)stock cpu fan
128Mb Mushkin PC133 HSDRAM
CLA2 Video Card
SBLive XGamer
CL 8X PC-DVD Player
1 old power supply fan used as a case fan
My CPU Temp ranges from 24C to 28C(AsusProbe)
My Mobo Temp is 28C(AsusProbe)
I just ordered a second Lasagna cooler Type B to replace the stock fan(crappy) on the CLA2 video card.

I have no lockups when playing Nascar Heat or NHL2001. I don't play Counter-Strike so I don't know about that!

With good ram and sufficent cooling it can be done.
Good Luck.