Why is my southbridge running hotter than my Northbridge?

I have a Asus P5B-Deluxe... I just felt (by hand) both of the chipset's heatsinks and the southbridge is on fire, can't touch it for more than 3-5 seconds. The northbridge runs much cooler. I've been having problems getting past 375MHz bus speed and I was wondering if the ultra hot southbridge was stopping me from going past 375MHz? Or maybe my P5B-Deluxe is wack..

i use to put a mini fan on it, but atm my temps are 30C (load) with HR-05sLI on NB stock on SB.

if you got a yate loon or extra fan laying around just put it there or in that general direction.... should cool it down....

well look at the heatsink difference in size.... and yes the sb will cause fsb limitations... on my p5wdh i couldnt get past like 430fsb even with maxed MCH voltage.... so i maxed out the ICH (sb) voltage and put a really high cfm 92mm fan blowing on it and whatcha know 445fsb without probs (for a 4ghz run of my e6600)

nd4spdbh2 said:

well look at the heatsink difference in size.... and yes the sb will cause fsb limitations... on my p5wdh i couldnt get past like 430fsb even with maxed MCH voltage.... so i maxed out the ICH (sb) voltage and put a really high cfm 92mm fan blowing on it and whatcha know 445fsb without probs (for a 4ghz run of my e6600)

Click to expand...

dam, and I've been spending all my time trying to cool down the northbridge, thinking that the southbridge won't affect overclocking... silly me..

If you look under the Advance tab in your BIOS,
go to "Chipset"

you'll see a rated FSB your actually running at.

I'm 340x9 and mine reads 1360mhz I believe.
(or did b4 I returned the board)

The 1360 is what the SB is being run at I think.
That's part of the reason it runs so hot.

This is a 965 chipset thing.
This is how they (Intel chipsets) are running so fast.

They slipped it in on us & let us find out the hard way about it.

Get a 975 board & it'll be just like the old days.
Going 965 is a Totally different beast.

I'm using Patriot Extreme LL memory, &
I maxed it out @ 1360 stable. not bad for rated PC800.

Get some extra cooling on your SB, it should help.

Here is a pic of the cpu/memory ratios or is that mem/cpu?
It may help you a little bit with the "Straps" on the 965.

Pic taken from the XS site.

WarriorII, I appreciate your thorough response.... Let me just understand this correctly. Are you saying that on a P965 chipset the southbridge runs at the same speed as the bus speed? If so I'm shocked.. although the burns on my finger make more sense now. hmmmmm.. the 975 chipset don't run the same way, why?

Let me find some of my research and I'll get back to you.

This also explains the other thread.... C2D vs PD.

The southbridge is running between 70-80C... Yet motherboard temp only shows 43C. I've read people saying that MB temp is south bridge temp, but this can't be true. I just ordered a 40mm fan for it.. I hope to bring temps down around 50C.. I hope this helps me get over the 375MHz wall I have. I haven't seen a P5B-Deluxe not do over 400MHz with a Quad, well except mine..

My ICH8R SB feels pretty darn hot, too... AS-5 plus a fan are in store for me, too

Maybe a larger heatsink, too. What would easily replace the stock Asus SB heatsink in a P5B/P5B-E w/o modification?

Anyone know if this would fit the P5B-E Southbridge (passive):
http://sidewindercomputers.com/encnfoconohe1.html




or this (active):
http://sidewindercomputers.com/minoxewh.html



Thanks

Randyman... After removing the northbridge heatsink, removing the crap on the bottom of it that asus used to stick to the chip and replacing it with AS5 and a 40mm fan, the temps are fine.. It went from burning hot to warm... I can live with warm... I put AS5 on the southbridge too, but without a fan on it the dam thing just burns me on contact.. my second 40mm should be here on friday that I'll put on the southbridge....

You know that the sad thing is.. that you spend almost $200 for a motherbaord that's high end and Asus uses the worst crap on the heatsinks.. I also want to mention the Northbridge heatsink was touching only about HALF of the chip's die. I was amazed. The southbridge heatsink is concave and they used this cheap thermal cement on it, I have to use a credit card and screw driver just to get the heatsink off.. I almost spent like $75 on stuff to cool the board, and then changed my mind.. AS5 and 40mm fans is all for me. Most of you know this but for those that don't know, the heatsinks on the Asus P5B Deluxe ARE NOT cooper, just cooper colored, they are aluminum. Also the cover on the Northbridge heatsink is just for looks but is terrible for cooling because it lowers airflow on the heatsink and insulates the heatsink. The cover is actually a metal sticker glued on.

I'm pretty sure you mean the SB heastsink is anodized aluminum, the NB heatpipe system is copper.

MadMan007 said:

I'm pretty sure you mean the SB heastsink is anodized aluminum, the NB heatpipe system is copper.

Click to expand...

Not really... The actual Northbridge heatsink is aluminum. The heatpipe and mosfet heatsink is cooper. I hope I cleared that up..

I guess I will try that. I certainly have some AS-5 laying around.

But does anyone know if those coolers I listed above (either one) will fit on the P5B-E SOUTHBRIDGE (ICH8R)? That passive copper one looks like it would help greatly, and it would get hit by the stream of air from the front HD Fan (more so than the "Low-Profile" Sink that comes stock on the P5B-E - the typical ICH NB Sink Asus has used on most 775 boards)...

My SB is really hot, and I'd prefer to avoid adding fans if possible. I strive for quiet PC's that still overclock like mad PS - I paid $82 for my Open Box P5B-E (had everything but a SATA cable wit it) But I also bought another one at retail, and a P5B-D WiFI retail, too - so I agree about the $200 comment...

Thanks!

Randyman... If you plan on using the 100% cooper heatsink without a fan, your temps will be higher than the stock aluminum heatsink. Passive 100% cooper coolers aren't that great, add a fan and then you're in business. If you wanna go fanless, go with aluminum, it will get rid of the heat quicker..

GigaHertzAddict said:

Randyman... If you plan on using the 100% cooper heatsink without a fan, your temps will be higher than the stock aluminum heatsink. Passive 100% cooper coolers aren't that great, add a fan and then you're in business. If you wanna go fanless, go with aluminum, it will get rid of the heat quicker..

Click to expand...

why is this?

nd4spdbh2 said:

why is this?

Click to expand...

The properties of cooper as a passive cooler will absorb heat faster than aluminum, but also retain it longer which in turn gives you higher temps than aluminum in a passive environment.

So the best bet it to use some AS5 on the stock SB Sink, and that's it? I was thinking that a taller Sink would get in the airflow from the front HD Fans. Any suggestions? Is the Active cooler I listed any better? I'm trying to keep it quiet, too...

What else will fit the stock SB Sink mounting holes?

My NB is already covered by the overhang on my XP-120 (blows right onto the NB Sink), but it will also get some AS5.

just use some as5... a lil airflow over it is all you need.

And the fact that copper holds heat better (because its more dense) makes perfect sence why aluminum beats it out in passive solutions.

FINALLY.. I have some real numbers... measured with a infrared temp gun. Voltages were kept on auto in the bios.

The southbridge temp on the stock heatsink and AS5 is 55C. By adding a 40mm fan to it they temps are around 40C. I'm sure the stock thermal glue Asus used was over 60C, but I can't go back in time and measure that. Keep in mind you have to add about 10C to the heatsink temp to get the actual internal chip temp. So the southbridge with the mod is running around 50C internal chip temp.. still hot. Also the southbridge ran 5C hotter going from 333MHz to 388MHz... I was surprised, but I guess bus speed affects the southbridge too..

The northbridge runs at 57C with AS5 and a 40mm fan on it... so I'd estimate the actual internal temp about 67C.. WAY TOO HOT!.. That's @ 388MHz on a Quad core... I took it down to 333MHz and I got 42C, so about 52C internal chip temp.. I can only imagine the temps with the stock setup..

I hope this helps...

Just for reference the way I got the 10C number is I took the temp at the center of my Quad core with the heatsink on... dead center.. and it was 10C less then core temp was reporting.

I will do more testing over the weekend, I gotta go because my girlfriend is waiting on my bed and is begging me to tweak her..

My old now P5B-Deluxe would run 50-60C on the heatsink with just a thermal probe in it. I had a 120mm fan blowing over the area to cool the dang thing and that was with the minimum voltage as well.