Higher CPU temps WITH AVC Sunflower

[stormont]

I have a Northwood 1.6A overclocked to 2.2. I was using the stock Intel heatsink/fan combo with the tim removed and the bottom of the heatsink lapped and TYpe 44 heatsink compound between the chip and heatsink. During 3D mark and Jedi Knight demos, the high temp was 118 and the average was 102. I removed the heatsink, cleaned the chip and mounted the Sunflower first using Artic Silver 2. Temps were then maxing at 131 and averaging 104. I removed the SUnflower, cleaned it, and applied the Type 44 coumpound and got the same results. Removed and cleaned the whole mess and re-installed the stock Intel HS/Fan and got temps as low as they were before. ANy ideas what's going on? I know the copper on the sunflower doesn't cover the entire heat spreader on the CPU.

 

[Mikewarrior2]

did you lap the AVC ?


Mike

 

[stormont]

Tried without lapping and then used 800 and 1000 grit paper on it. Same results.

 

[WarCon]

Double check the mounting bracket to make sure its seating correctly. The stock heatsink is designed to apply 100 pounds of pressure (which is what flexs the mobo's so much). If it doesn't look like the AVC is doing this then it may not be on correctly.

 

[stormont]

WarCon, that's an interesting idea. The mounting system for P4 coolers is standard, right? When I installed the Sunflower, I left the bottom half of the bracket that came attached to the motherboard attached since it was working fine with the old cooler. I haven't removed the board from the case to see if the SUnflower is bending it as much as when the stock cooler is mounted. The one that came with the Sunflower shouldn't be a differnent height should it?

I would have assumed that through all of my testing with thermal compounds, at least one of the times the heatsink got seated right, but every time my temps were always higher.

 

[WarCon]

Actually its supposed to use the same bracket. The AVC's lugs have been reported to be a little higher than the stock cooler's which can make them a little difficult to undo, but that also made me think that its possible that maybe one of them isn't locking in correctly and is causing uneven pressure to be applied.

 

[stormont]

So I completely removed the motherboard and took a look at what was going on. I looked at the bend of the motherboard with the stock cooler installed and then looked at the bend with the Sunflower installed. The board was bent noticeably less with the Sunflower installed. I removed the stock HSRM, and held it next to the one that came with the Sunflower. They were exactly the same size. I installed the one that came with the Sunflower and again compared the bend with both stock and Sunflower heatsinks installed. Same results, less bend with the Sunflower.

While I had everything apart, I took the time to finish something I'd stumbled upon when lapping the heat spreader on the 1.6A. I had sanded a little too much nickel off and noticed the copper underneath. I completely lapped the speader down to a complete layer of copper. I then used Type 44 Heat-sink compound applied to the bottom of the slug on the Sunflower, not all over the heat spreader. I had noticed that the Sunflower core does not completely cover the heat spreader and figured that any coumpound that was installed on the spreader and in contact with the Sunflower was acting as an insulator.

Put the whole mess back together and now under load, the CPU (1.6A running at 2.1) runs at 48 degrees celsius. I figured the copper to copper contact of the spreader and Sunflower should have it lower. I might try re-installing the stock Intel heatsink (which I took the TIM off of and lapped before I ever used it) and see how much lower it is now. Or I might wait for a response to my other post about where to find the cheapest place to buy an 8942.

 

[WarCon]

That isn't an unreasonable temperature, but if thats what your stock cooler was doing then the AVC just isn't doing the job it's suppose to be able to do. Thugsrook (hes at 176fsb) has been getting fabulous temps with the Alpha cooler that your looking at, so that might be a good direction to look.

 

[WarCon]

I just thought I would mention this for something to think about just in case.

There is a direct relationship between ambient (room temp), case (system) temp, and CPU temp.

Example - Room temp 20C, case temps (on well ventilated case) typically 3-4C higher for 24C, then CPU temp at full load is based on power usage (lets say 100W for easy math) * the cooling capacity of the heatsink (C/W) which lets say for a decent one is .15 C/W = 15C which is added to case temp since thats the air you are using for a expected CPU temp of 39C. Thermal compound may vary this slightly since it has its own C/W rating.

 

[stormont]

Have to bring a thermometer down for the room temp, but the case temp is 28 degrees celsius. PC is in a basement with no HVAC ducts, just natural cooling. I'm going to try sticking the stock cooler back on and see what I get.

 

[Jgtdragon]

I also installed the Sun Flower with Artic Silver 3 lastnight. My temp went up by 2C. I notice one thing between the two hsf setup. Intel stock blows air onto the heatsink while Sunflower suck air from heatsink. Did you switch the fan direction on the sunflower to blow onto the heatsink? That might help.

 

[tracerbullet]

You probably do this - but when you lap, make sure it's on a very flat surface. I pull the glass top off of my fishtank and place sandpaper on that when I do mine.