Thunderbird 850 (new to overclocking)

Hey, I read an article in Maximum PC yesterday that told a bit about how to overclock AMD chips. It told about using a pencil to connect the proper dots on the back of the chip, which sounds simple enough. I'm thinking about doing it, but if you guys could answer some questions for me that'd be cool!

I'll start with my specs:
AMD Thunderbird 850Mhz
Future Pro VIA KT133A mobo
768 MB RAM
Standard fan/heat sink



Once I connect the dots, how do I actually force the chip to run at a higher rate? I go to BIOS and just change the chip speed to whatever I prefer? If so, how high do you recommend I set it? Could I go as high as 1 gig? Right now the temp is 30 Celsuis. My VIA hardware monitor says that overheating would be around 50 Celcius...

So can I get away with overclocking it, without purchasing a better fan/heat sink? Is there anything else I should do besides connect the dots and raise the speed? What about voltage, do I have to mess with that somehow?

Thanks in advance for any help you guys can give me!

Im not familiar with the motherboard youre using (Ive got an abit kt7-raid) but if it supports cpu fsb and multiplier settings to be changed in the bios, that is all you do to overclock. so, you do the pencil trick, plug everything back in and boot up. head into the bios. ive gotten my 1.1 to 1.2 before... but ive got crappy cooling so i leave it at 1.1. however if youre running at 30c (im assuming thats idle temp) -- you could proly push it to 1g or more. good luck.

One extra tip: overclock slowly and make sure your temps are still reasonable at each step. This will help prevent burning out your cpu by bringing the speed up too high. At 30C, you could probably jump it up to 950 before starting to check temperatures.

If your motherboard supports it, start out by increasing your multiplier and finding the maximum stable speed you could run your cpu at. Once you have found how far your cpu can go, drop it back down to 850 and begin increasing the fsb. Find the maximum speed your fsb can run stable at. If this number is below the maximum speed you found on your cpu, then keep the fsb speed and overclock the multiplier until you can reach that max cpu speed again.

Something else you may be able to look at is lowering latencies on your ram. I don't have much experience with that though.

If your motherboard doesn't support multiplier changes (mine doesn't), just up the fsb until you hit your max stable range.

If your motherboard doesn't support fsb changes in the BIOS, you get to start screwing with jumpers.

What else is there to say? Oh yeah, make sure to test your cpu running under load for at least a couple hours before making any changes that are a bit iffy.

Excellent! Sounds like this won't be QUITE as engineer-technical as I always feared it was lol.

OK couple more things:
This mobo has a FSB jumper setting, right now it's 100 mhz, I can set it to 133 but then the system hangs at startup. Tech support said this is cause the Thunderbird doesn't run at 133? That sucks So should I try messing with that?

Also what's this with the multiplier? I dunno what/where that is...

So lets say I start out by jumping to 950 mhz, and things look ok, temp presumably goes up a bit... How high do you think it's possible to (safely) take it? Could I get to 1 gig or more??

First of all welcome to the forums!

What is the motherboards brand & model, what is ur CPUs steppings? But AFAIK, you could get 1Ghz out of it.

Good luck!

one thing to remember...

Something you might want to keep in mind is that as you increase the FSB settings, you are not just doing so for your CPU. You are putting added stress on every other component that runs on that clock. i.e., ram

If your comp doesn't like running at 133, try bringing the fsb up by a smaller amount if possible. If 100 and 133 is all you can do, it's time to screw with multipliers or possibly bust out extreme cooling solutions.

Oh, and here's the basic definitions of multipliers and fsb

fsb: front side bus - basically your big system pipeline that everything is pushed through. The two things that hinder your fsb the most are memory modules and cpu. If both of these can handle a higher fsb, you should be ok.

multiplier: the internal frequency of your cpu. Everything outside runs at 200 or 266 (100 or 133 fsb), which is obviously less than the megahertz your processor is able to do. The way you tell the cpu how much higher to run than the stuff outside it is by the multiplier. The frequency of your cpu is calculated by multiplying the fsb by the multiplier. In my case, my cpu runs at 133fsb and 10.5 multiplier, which is 1396.5Mhz (1.4Ghz). I upped my fsb to 145 and now it is 10.5*145, which is 1522 Mhz.

If the rest of the system can't handle a higher frequency, you can increase the multiplier to get a faster cpu frequency.

Increasing the fsb gives a better performance boost than increasing the multiplier. the multiplier just affects the cpu, while the fsb affects the computer as a whole.

Be careful when overclocking! Around here everyone starts to get kind of casual about it, but I have heard some horror stories once in a while: things like penciling the L1's and crossing them=burned chip! I'm not saying don't do it by any means: I've got 3 oced rigs running now: just read up on it first, and then TAKE YOUR TIME!

There is all kinds of good info in the Beginner's Guides here: http://www.overclockers.com/topiclist/index04.asp#BEGINNER GUIDES
and elsewhere.

I've been slowly getting a 900 Tbird overclocked for a few weeks: right now @1.1, but I'm hoping to get more in time.

Good Luck!

Interesting! So it'd be in my best interests to figure a way to get the FSB up, huh? But the tech support dudes told me that the Thunderbird chip specifically does not support a 133 FSB. I can easily just change the jumper on my board to 133, but when I do that (tried it several times) the system just doesn't start up. It's annoying cause my RAM is all 133, so it'd be nice if my system could run at the speed it's capable of.

How do you guys get your thunderbirds to run at a faster fsb speed?

I might not want to get into that anyway, though.. I don't plan on getting a better fan or heatsink or anything--I just wanna push this a little further without going all out and stuff, y'know?

Mike521 said:

Interesting! So it'd be in my best interests to figure a way to get the FSB up, huh? But the tech support dudes told me that the Thunderbird chip specifically does not support a 133 FSB. I can easily just change the jumper on my board to 133, but when I do that (tried it several times) the system just doesn't start up. It's annoying cause my RAM is all 133, so it'd be nice if my system could run at the speed it's capable of.

How do you guys get your thunderbirds to run at a faster fsb speed?

I might not want to get into that anyway, though.. I don't plan on getting a better fan or heatsink or anything--I just wanna push this a little further without going all out and stuff, y'know?

Click to expand...

Your CPU certainly does not dictate what FSB your system can run at...the "tech support" were just feeding you a line. If your motherboard doesn't have a /4 PCI divisor then you just might be out of luck. The reason you're not able to run it is because your chip will probably not get up to 1130MHz...the older Tbirds just don't handle it that well. You *might* be able to manage it if you get into some heavy duty cooling...

There's also the question of what your mobo has in the way of overclocking features (vcore, vio, mult, FSB functions)...and the fact that you still have stock cooling isn't the best either.

Check out the front page for oodles of information on stuff, see what you can find out about your board (sounds like it probably doesn't have many options) and maybe do a search on the different bridges of your chip...you can change the vcore and mult by joining and breaking certain bridges. You have to be kinda gutsy to do that one, though.

OK guys couple things I don't understand:
If my chip ISN'T what is stopping my PC from running at 133 fsb, than what IS? My memory is all 133...
I know my chip isn't one of the faster Thunderbirds, but it's not "old" either, I just purchased it this summer. So going by what the Maximum PC guys said, chips being made now at 1 gig could just as easily have been sold as 1.2 gig processors, cause "AMD improved its Thunderbird process technology and began spitting out CPU's with more frequency headroom."
But it still never made sense to me that my chip couldn't run at 133, considering that busses are much faster than that nowadays.

As for my motherboard, I'm not too sure on any of the specs of it really. It was cheap, if that tells you anything. It's a Future Power KT133A VIA chipset..


Well anyway, wish me luck, I'm gonna overclock my multiplier now!! I'll start out by bumping it to 950, and leave it at that for a day or so and see how things look. If I don't post here again for a week, it means I fried my system LOL!

OK this is WEIRD. I think I did it right. Benchmarking programs are saying I'm running at 917 mhz right now. The weird thing is, my system temp, as reported by my VIA health monitor, has gone DOWN?!? It's reporting 26 - 26 Celcius when not under load, as compared to 31 - 32 Celcius before the overclock.

Well I'm happy LOL

Once my system didn't boot and I thought I'd screwed up. Dunno why it didn't boot, but I switched off the main power, switched back on and hit power switch and it got me to the BIOS, where I lowered the overclock down by a couple notches (107/35/off--I think), and it's working fine now.. Neat
I also used some kinda software program to overclock my video card from 115 mhz to 130 mhz. Yay!!

If this runs well for a couple of days, I'll try bumping it up a bit more. What do you guys think about the temperature thing??? I mean that's the opposite of what should be happening, right?!

The reason the pc hangs at boot when selecting 133 fsb is because that chip can't handel 8.5x133 once you unlock it with the pencile trick or what ever you prefer it will run at 133 with a lower multiplier, start at 6 or 6.5 it should be able to handel those. I had an 850 and with a volt mod and good cooling it went to 1150 11.5x100.

OK it's overclocked, but I can't seem to change the multiplier in BIOS, all I can change is the FSB. Every time I bump that up by one or two, it ups my CPU. But I'm getting a lot of freezups when I play Tribes 2, consistant freezes. My video card isn't spectacular, so I don't think it agrees with the faster FSB? I dunno, but this is annoying. Why can't I just up the multiplier and leave the FSB alone? I might have to just leave it at 900 or even worse, the 850 that I bought it for