Mosfets on P5N-E SLi

topgun06

topgun06

topgun06

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Just brought the Asus P5N-E SLi motherboard. I knew that the southbridge didn't have a heatsink but i was supprised to see the mosfets without anything to cool them. I am planning to get some high overclocks out of this rig and would i be advised to get some cooling fitted to the mosfets at least. Im sure they will get hot, especially when overclocking. What about the southbridge?

Thanks.
 
Just to get this right - the Southbridge is the big black chip down by the SATA sockets - yes?

I'm only asking because everyone is saying theirs get's very, very hot, but mine is cool to the touch.

The big central Northbridge cooler gets very hot with the 1.5V setting applied and it can become untouchable with the 1.7V setting applied but the 'system' temperature (which comes from the Southbridge sensor apparently) is reading 34C on my system.

I was also surprised that the PWM system has no heatsink (both the P5ND2-SLi and the P5N-SLi had 30x10x20mm heatsinks on the PWM MOSFETs but they're not massively hot - and I'm on passive water cooling so there is no CPU fan blowing across them. I will be water cooling the Northbridge in the very near future as having a fan running is really doing my head in.

I've been running at 3.4GHz for a couple of weeks now after trying reasonably unsuccessfully to get my E6600 CPU stable over 3.8GHz (It will boot into Windows at 4GHz, but hangs fairly rapidly thereafter) and 3.6GHz (which I can run absolutely stable) gives me CPU core temperatures over 70C under load with my passive water system so I've dropped it back to 3.4GHz for safety.

The surface component temperatures are certainly no worse than a DS4 this has replaced.

What it boils down to is;

1. Do you think ASUS would release a board to the market that would overheat itself to death?
2. Buy it from a reputable supplier
3. Keep the receipt for RMA purposes
 
Agreed, the SB doesn't get at all hot on these boards.
Mosfets are warm, but not overly worrying. Sink's on them tend to do jack all anyway tbh, often insulating the heat rather than removing it.

Last exam today, so will run some tests and get the temps of the mosfets for you, along with the southbridge.
 
If you want to cool MOSFET's (and gate drivers where applicable) put a fan blowing onto the board, as OC_A64 said dont "heatsink" them...

The active silicon is bonded to the metal tab and packaged in the black ceramic material. They are designed to dissipate power through the metal tab to the large ground / power planes on the PCB, if you want them to run cooler, cool the planes.

The maximum opperating temperature is very high, in fact it's so high that they will desolder themselves before they fail :)
 
Oh ok then.Thanks for the help people :D

I was going to get a cheapo heatsink and mod it for the mosfet.
Ive seen a PII Xeon heatsink flaoting around... but seems a bad idea now.

Looks like i should be ok to just get overclocking!
 
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That system temp is just the temperature for the case imo

Ive no idea what the north or south bridge temps are really since there is no gauges for them on this cheap board.

At present Im trying to get this thing to clock so Ive been forced to try 1.5v on the northbridge.
Ive got two 80mm on that heatsink and then two just after it, emptying the case of hot air.

The southbridge burns my hand, quite surprising as it was cool before. It has no heatsink or fan near it so I will have to remedy that

I estimate the bridges to be about 50 or 55c. I guess thats an exceptable
temp to have. The core temp is 63 under orthos at a reading of 1.41v and its 1.46v at idle


The mosfets feel fine, body temp I'd say and they have lots of air flow over them.


Can anyone say what voltage I can use roughly on budget noname ddr2 ram ?
I have it at 2v with a 92mm fan just in front at 5v
 
WJA96 said:
What it boils down to is;

1. Do you think ASUS would release a board to the market that would overheat itself to death?
Click to expand...
They've done it before.
A friend had an asus board (i forget which model, but fairly recent) which would die after about a days use due to an inadequate chipset heatsink. He went through 4, we put a fan on the fourth and its been fine since, the first 3 were rma'd. Then theres also the a8n sli deluxe, which had a very poorly designed chipset cooler, many of which failed very early on, and resulted in asus redesigning the chipset cooler and replacing the old ones for free.


Careful with heatsinks on mosfets because the casing is very often 'live', so you have to use a special thermal pad which is also an electrical insulator. If you don't you could short them. If its under warranty just ensure good airflow and leave it alone. Mosfets are fairly robust and are fine with quite high temperatures. If you can find a part number on the mosfet itself you could even try punching that into google and have a look at the spec sheet, that will list the maximum temperature.
 
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