Cooling a hot CPU in hot weather

[Funky D]

Hi all,

I have a very hot 3.2GHz prescott cooled by a Thermalright XP-120/Papst fan @ 7v. I had to turn off thermal throttling in the BIOS as the chip would throttle all the time, but the system has been solid over the winter (ambient temp of around 18C). Now that things have been warming up, my system has been shutting down under load (ambient temp around 25C). A quick check showed the chip idling around 64C, and I don't want to think of how hot the thing is getting under load!

I've done all I can with the XP-120... reseating, fan @ 12v, faster/noiser fan, etc etc. Makes no difference. I was wondering if upgrading the heatsink to say, a Tuniq Tower would make a difference? (one of the only new heatsinks that supports the 478 socket, it seems)

Temp of the motherboard (northbridge?) is 35-40C... temp of my ATI X1950Pro is 60C under load. I have intake and exhaust 120MM papst fans running @ 7V. Case is an Antec SLK3000B. This damn Prescott chip has been a nightmare!

What do you guys think? New heatsink worth a shot?

Thanks!

Paul

[jaganath]

This damn Prescott chip has been a nightmare!

What do you guys think? New heatsink worth a shot?

new(ish) CPU also an option, you can probably pick up a Northwood on Ebay for same $ as a Tuniq Tower.

[jhhoffma]

If you're not careful with the SLK3000B, you'll end up recycling a lot of the hot exhaust air from the CPU and actually heating up the rest of your components.

I got tired of the constant dust problem with an excessively negative pressure case so I close off the side vents (removed the CAG), opened up the back slot-covers underneath the vid card (as a secondary intake) and used a front-to-back aiflow for my system. Even though there is less intake area, the system runs cooler.

Northbridge cooling is VERY important for system stability (as any OC'er knows), so keeping this cool is a big concern. Separate air paths help. By ducting a tower CPU heatsink, you may be able to keep the CPU heat from being recycled to the rest of the system.

Sorry if my thoughts are all over the place, I'm typing in a rush.

[angelkiller]

If you're not careful with the SLK3000B, you'll end up recycling a lot of the hot exhaust air from the CPU and actually heating up the rest of your components.

Yes, ducting is very cheap and effective way to help temperatures. (If done correctly) At worst you lost ~2 hrs and some cardboard.

In your situation I cannot recommend a new heatsink. Yeah the Turiq is massive and will help with temperatures, but if you're idiling at 64C with aftermarket cooling, the Turniq may only get you down to ~60C. Either way it's hot!

For you I'd recommend a new motherboard and CPU. specifically, a AM2 mobo, (Any with AMD's 690G or 690V chipset) and a Athlon X2 3600. Plenty of great reasons to go this route. The X2 will run much much cooler than your P4. The X2 will also give you a nice performacne boost. You will also have a more modern system, that is very upgradeable. And this is all for about twice the price of the Turniq. (Did I mention you will see much lower temperatures?) You'd idle probably in the 30's. I've seen an overclocked X2 3800 cooled by a Ninja idle at 31 and full load was 55. (with 21C ambient) You can also reuse your XP-120 with Thermalright's AM2 adapter. Hope some of this helps.

EDIT:Have you tried reseating your XP-120? Just thought of that. You may not have good HSF/CPU contact.

[Hardtailed]

Let's see, I have a Prescott 3.0 in an SLK3000B with just the stock Tri-cool fan on Low. Was running fine on stock HSF, replaced recently with a Scythe Andy Samurai Master which is running at roughly 1000RPM (can't hear it!)

Let's see, CPU is currently at 26C according to Speedfan. I never saw it touch 40 under load, even with ambient at 25-26.

I didn't do anything special... the Scythe is sucking air right from the side vent (tried to block it, mobo temp went up 10 degrees and HD didn't go down so left it open) and then is exhausted via the Tri-cool and the PSU above it (Corsair).

So I don't know what to tell you... the .2 GHz difference can't explain such a difference. Is there enough clearance on the left side (where the vent is)?

[jhhoffma]

Let's see, I have a Prescott 3.0 in an SLK3000B with just the stock Tri-cool fan on Low. Was running fine on stock HSF, replaced recently with a Scythe Andy Samurai Master which is running at roughly 1000RPM (can't hear it!)

Let's see, CPU is currently at 26C according to Speedfan. I never saw it touch 40 under load, even with ambient at 25-26.

I didn't do anything special... the Scythe is sucking air right from the side vent (tried to block it, mobo temp went up 10 degrees and HD didn't go down so left it open) and then is exhausted via the Tri-cool and the PSU above it (Corsair).

So I don't know what to tell you... the .2 GHz difference can't explain such a difference. Is there enough clearance on the left side (where the vent is)?

But do you have an X1950Pro pumping out a buttload of heat? These cards don't exhaust air out the back of the case like their higher-end brothers. And with all of the hot air going back into the case, it eventually makes its way to the N/B - S/B area and stays there, causing the system to become unstable.

[angelkiller]

But do you have an X1950Pro pumping out a buttload of heat? These cards don't exhaust air out the back of the case like their higher-end brothers. And with all of the hot air going back into the case, it eventually makes its way to the N/B - S/B area and stays there, causing the system to become unstable.

Very valid point, but look at my system. I have a PD running faster than his P4. So essentially I have 2 65nm P4's running faster than his 90nm P4. And we both have X1950pro's. (In fact mine is slightly OC'ed.) My PD idles at ~43C. I've seen loads close to 70C before. My ambient is ~23C.

So yes the X1950pro will dump lots of heat onto the CPU, but not that much heat.

[Funky D]

Thanks for the replies everyone... I really think I just got stuck with a hotter than average chip. I never thought of going the ebay route for a used northwood... thats a good idea! I'm not up for the hassle of a motherboard swap, but it looks like the 3.2GHz northwoods can be had for $20-40 more than a Turniq. Not too bad.

I have the HIS X1950Pro, so it actually does vent outside the case. I used to have a passive 9800pro with an 80mm fan mounted next to one of the side vents, but after upgrading and ditching the fan, I guess I could try closing off the side vents to see what that does for temps.

My case is probably warmer than most (I also have 2 audio DSP cards that get somewhat toasty), but I can crank all the fans and still see over 75C on the CPU when under load. To think I could have spent $10 more for a Northwood when I bought the stupid thing

Thanks again everyone, lots of good info... I'll post a follow up if I get a new chip

[Funky D]

Well, I bid on a 3.2GHz Northwood on eBay and received today. I anxiously swapped chips and got to testing. Here are the before and after results:

Before (Prescott):
60C (Idle)
85C (Load, just before system shut down)

After (Northwood):
50C (Idle)
75C (Load, just before system shut down)

Ugh! Not very good, eh? I reseated the heatsink, switched the fans to 12V... no luck. FINALLY, I tried doing what I should have done months ago. I tried the stock HSF. Results: 36C (Idle), 49C (Load).

So it was a bad XP-120 all along... Looks like I should have went with the Tuniq instead of the Northwood At least my system will run cooler overall with the new chip, and I can sell the Prescott on eBay knowing there is nothing wrong with it.

What a bummer though, I'll need to buy a new heatsink anyway. I'll probably just get another XP-120, since it's so easy to install and I'm sure the chances of getting another bum one are slim. The sad thing is, I'm pretty sure this heatsink was bad all along and I could have RMA'ed it when I still had the chance. I missed the problem early on because the system was throttling, and after I turned throttling off I was lucky enough to stay just below the shutdown temp most of the time.

Well, this ends the saga I guess. I need a new heatsink soon, this damn stock HSF is driving me mad already!

[kater]

Funky D - and what, do you think, actually is the problem with the heatsink? Faulty pipes? Imperfect cooler/CPU contact surface? Bad fin/heatpipe contact?

[Funky D]

Kater, I can only assume it's a problem with the heatpipes. The contact surface is smooth and flat, the retention brackets hold down tightly, and the thermal compound spreads out evenly as you'd expect. The heatpipes were lukewarm to the touch at idle, and at load were just about as hot as the fins (but not as hot as I would have expected for a chip running at 85C). I don't know enough about heatsinks to narrow it down, but I after a bit of searching found other people who've had the same problem.

[fractal]

Are you sure your problem is the heat sink and not the case?

My first guidance to anyone in your situation is to eliminate the case by removing the side of the case and blowing a house fan into the case. If this (brute force test only experiment) fixes your problem then your issue can be resolved by properly ventilating your case. If this does not solve your problem, then something else is going on as that HSF should keep that chip within 15c of ambient ( http://www.silentpcreview.com/article186-page4.html ).