Help With 1700+ T-Bred 'B'

[MeTaLrOcKeR]

I just today baught a T-Bred 'B' 1700+ JIUHB 0302 Processor....it runs at 1.6VCore stock.......

right now shes running at 28 degrees celcious under full load with the EXACT same cooling as my T-Bred 'A' 1800+ had...but now I've overclocked the thing to 1940MHz.... 12.5 Multiplier and 155MHz FSB.......

Here's my question....my Motherboard is the ASUS A7S333...with the SiS745 chipset...my experience shows this chipset doesnt like being pushed to much above 155Mhz....158Mhz MAX FSB.....so i need to OC VIA Multiplier.....now....just like my T-Bred 'A' I dont have the option in my bios for ANY Multipleir above 12.5.......so how do i do this ??? I know with a T-Bird 1.333GHz AYHJA i had like the options 13.0, 13.5 and above..but right now it doesnt....i wanna see how far this can go...i mean i only paid $109 CDN for this 1700+ T-Bred 'B' Retail........so far its running great.........but i want it to go higher!

Its running Uber cool and Uber fast right now.....but i know theres a lot more in this thing.......keep in mind the voltage is still at default and i cant chaneg ti with my motherboard...it has no voltage adjustments.....but i can chnage the FSB and Multiplier......and changing to 166MHz FSB is out of the question.......this chipset doesnt have a 1/5th PCI/AGP Divider lock......


<A HREF="http://www.anandtech.com/mysystemrig.html?id=13597" target="_new">-MeTaL RoCkEr</A>

 

[phsstpok]

OK here's what I know so far. Be warned this is regarding VIA mobos (KT133, KT133A, KT266, KT266A, KT333). Haven't heard anything about SIS mobos yet.

Without BIOS multipliers of 13.5x-24x there is only one thing that can be done, mod the chip. By cutting the 5th L3 bridge you gain access to the higher multipliers but it's not as simple as you would hope. (I'll explain this in a bit).

After you boot you run into a remapping problem. If you set your multipliers in BIOS and FSB to 100 Mhz you'll get the following remappings.

7x ----> 15x
7.5x --> 22.5x
8x ----> 16x
8.5x --> 16.5x
9x ----> 17x
9.5x --> 18x
10x ---> 23x
10.5x -> 24x
11.5x -> 19x
12.5x/13x -> 20x

That's the good news the bad news is it only works with low bus speeds 100+ mhz. At 133 Mhz you are stuck at the default multiplier at which you mod'd your chip. Don't know why this is true.

This fact makes it important to choose your default multiplier wisely. I liked 15x because 15 x 133 is 2000 Mhz a decent overclock yet still within the capabilities of Tbred B 1700+. If you want to use a higher bus speed you'll want a lower default multiplier but remember you won't be able to change the multiplier from BIOS any longer so too low a multiplier may limit your overclock. 15 x 133 gives a good starting point, 2000 mhz (XP 2400+). Overclocking the bus from there lets you get into the typical Tbred B 1700+ overclock levels. 150 Mhz gets 2250 mhz. 160 mhz gets 2400 mhz which you probably can't get much higher with a 1700+.

2250 is my max with a rather high 2.15 VCore but I've settled on 2100 mhz, 15 x 140. I've only tested with KT133 and KT133A mobos but I've read that people have run into the same issues with KT133E, KT266, KT266A, and KT333 mobos.

If you want to try the same multiplier (15x) then the L3 bridges should look like this C--C--C--O--O. For an XP1700+ you need to cut the 4th and 5th L3 bridges.

So far I've only read about people using Tbred B 2100+ and 2400+ and XP 1700+ or XP 1800+ being mod'd to look like one of the first two.

Once again I'll mention that so far I've only read about VIA mobos.

Head on over to Usenet (I use Google Groups) and the alt.comp.hardware.overclocking.amd news group if you want to learn more about overclocking Tbred B's




<b>99% is great, unless you are talking about system stability</b>

 

[MeTaLrOcKeR]

ahh.....Thats some very good information phsstpok.......thank you VERY much.......the problem i have with cutting the bridges is for one, i dont know how far down to cut or if its gonnna damage anything if i cut to far...and also....lets say i wanna put it back to normal so i can access the other multipliers again.....what than ?

<A HREF="http://www.anandtech.com/mysystemrig.html?id=13597" target="_new">-MeTaL RoCkEr</A>

 

[phsstpok]

I didn't know how deep to cut either. You can't see what you are cutting. One thing though, the material is pretty hard to cut. Slow progress works in your favor. Make your cuts. Test the CPU. If it doesn't work cut a little deeper. Test again. Don't forget to cleat CMOS each time. Your cutting guides are the trenches on the other bridges. You don't have to go as deep but you certainly don't want to go any deeper.

I cut about 10 times with a razor blade and it worked on the first test but maybe I got it on the first cut.

As for returning the CPU to normal, you could fill in the cuts you made and then reconnect the bridges with with conductive paint. Alternatively, you don't fill the cuts and just do the "U" trick on the 5th L3 bridge. With the L3 bridges now at C--C--C--0--C you have only a 7x multiplier but BIOS multiplier adjustments (5x-12.5) will once again work.

<b>99% is great, unless you are talking about system stability</b>