Alpha S-PAL8952 P4 Heatsink

Cooling
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ASSEMBLY

The Alpha S-PAL8952 heatsink was mounted on my standard P4 motherboard. Assembly was not as easy as with heatsinks that utilize the stock Intel mounting bracket, but wasn't difficult for me because my test setup is not mounted inside a case. I didn't need to remove the motherboard before installing the standoffs.

The instruction sheet is well-illustrated as easy to follow. A couple of adjustable crescent wrenches or 9/32" and 7/32" nut drivers are very useful to tighten up the standoffs and locknuts to the board.


Standoffs bolted to the board. Note the nylon washers. Threaded end of standoffs extend through the board and are bolted on from underneath using the included flanged locknuts and another set of nylon washers.

After mounting the standoffs, apply the thermal compound to the CPU and insert it into the socket. Then bolt the heatsink onto the standoffs. The four spring-loaded bolts apply the correct amount of pressure. The standoffs themselves provide the correct height. This is a safe and foolproof mounting method, as long as the screws are tightened in a "crisscross" pattern to keep even pressure on the CPU. Combine this with the security of the "bolt-through" method of attaching the heatsink to the board and you have one of the best mounting methods available.


Completed mounting. Fan shroud channels air in through the warmer base of the heatsink and acts as a spacer to raise the fan above the fins.

ON THE TEST BENCH

I compared the S-PAL8952 to my sort-of-reference Zalman 7000AlCu heatsink, as well as the stock Intel P4 heatsink. I used the same processor that I've been using in all my heatsink tests, a P4-2.4C. It may not put out as much heat as a new Prescott, but using this processor will allow me to directly compare the performance of the new 8952 against all the other high performance P4 heatsinks that I've tested during the past year.

I also tested the 8952 with the SPCR Reference 80mm Panaflo L1A. This will let us directly compare the cooling ability of this heatsink against other heatsinks that we have tested with the Reference fan, as per the basic SPCR heatsink testing philosophy of keeping everything the same (including the fan) and changing only the heatsink. The Sanyo Denki and the Panaflo L1A were both tested blowing down on the HS as well as blowing up. In both cases the performance with the fans in the traditional "blow down" method ran about 2-4°C hotter than when they were used the way Alpha engineered them. The Zalman 7000 and stock Intel coolers were tested with the fans in their normal "blow down" orientation.


Ye Olde Test Setup

Key Components in P4 HS Test platform:

The P4 HS test platform is an open system not enclosed in a case.

Intel P4-2.4C Northwood core - Maximum power is 66.2W.
Intel 875PBZ motherboard - Intel 875P Chipset; on-die CPU thermal diode monitoring
ATI Radeon 7500 passively cooled video card (AGP)
Mushkin PC3200 Level II - 2 x 256MB DDRAM
Seagate 80GB Barracuda IV hard drive
Seasonic SuperSilencer 400W (rev A1) PSU
Arctic Silver Ceramique Thermal Compound
Two-level metal platform with rubber damping feet. Motherboard on top; other components below.
CPUBurn processor stress software
Motherboard Monitor 5.3.4.0 software to track CPU temperature and fan speed

Each heatsink was cleaned and installed on the test system as per the manufacturer's and Arctic Silver's instructions. Prime95 was then run for 8 hours to verify system stability and cure the Ceramique. The system was then shut down and not restarted until the next morning when the actual testing was done. The system was allowed to cool between tests for 30 minutes. Each test was run for 30 minutes even though all temperatures generally stabilized within 15 to 20 minutes.

Each heatsink was tested three times on consecutive mornings to check to the consistency of the results. All results were within 1-2°C of each other and the average readings are included in the charts.

Ambient temperature was measured at 71-72?F (22°C) over the entire series of tests. No tests were run unless the ambient temperature was at that reference level.

* All temperatures in degrees Celsius.
* Diode: Reading from P4-2.4C CPU diode via Motherboard Monitor.
* °C Rise refers to the difference between ambient temperature and the diode reading. .
* °C/W refers to the °C of temperature rise per watt of heat dissipated by the CPU.

RESULTS

I tested both the included Sanyo Denki fan and the Panaflo L1A at a fixed 12V, as well as at the quieter settings of 7V and 5V. The 12V results are shown below:

A) 12V Fan Results
Heatsink
idle
load
°C rise
°C/W MP*
°C/W TDP*
Alpha 8952 w/ stock fan
25°C
41°C
19
0.25
0.29
Alpha 8952 w/ Panaflo L1A
27°C
42°C
20
0.27
0.30
Zalman 7000
24°C
40°C
18
0.26
0.27
Stock Intel HSF
25°C
46°C
24
0.34
0.36
*For °C/W - TDP calculations, Intel's TDP of 66.2W was used.
*For °C/W - MP calculations, CPUHeat & CPUMSR Projects' estimate of 75W was used

At 12V the 8952 with the stock Sanyo Denki fan performed well but was also fairly noisy. It had a fairly noticeable whine and a moderate amount of rushing air noise. It's definitely too loud for a quiet system but it cools surprisingly well for being such a low-airflow fan.

Next I swapped out the Sanyo Denki fan for the 80mm Panaflo L1A, running at 12V. It cooled the CPU virtually as well as the stock fan with less air turbulence noise; the electrical/mechanical noise was less objectionable as well

At full speed the Intel HSF sounded worse than the stock Sanyo Denki fan and it didn't cool as well. It's as expected, running in such high class company.

The Zalman at 12V was certainly audible, but not as objectionable as the stock fan or the Panaflo at 12V. The Zalman cools as well as the 8952 with noise lower in level and pitch, but still not acceptably quiet by SPCR standards.

B) 7V Fan Results
Heatsink
idle
load
°C rise
°C/W MP
°C/W TDP
Alpha 8952 w/ stock fan
27°C
50°C
28
0.37
0.42
Alpha 8952 w/ Panaflo L1A
28°C
52°C
30
0.40
0.45
Zalman 7000
24°C
41°C
19
0.27
0.29
Stock Intel HSF
28°C
55°C
33
0.47
0.50

At 7V the Sanyo Denki fan was much quieter than at full speed, with considerably less whine. The air turbulence noise was also noticeably quieter. I heard just the slightest bit of clicking, but only at within about 6" of the fan. At 7V, the Sanyo Denki sounded a lot like the Panaflo L1A at 7V, but with less clicking than the Panaflo.

The 8952 was a decent performer with the Panaflo L1A at 7V. The noise was pretty low and probably wouldn't be objectionable for most quite PC enthusiasts, as long as they aren't real sensitive to the quiet clicking noise. Chances are it would be muted by the case and noises from other components. The 8952 would certainly be suitable for cooling a 70-80W P4 with either its included fan or the L1A Panaflo running at 7V, and both fans are very quiet at those settings.

The Zalman still worked better at 7V and its noise was pretty unobtrusive, consisting of a bit of air noise and a quiet clicking.

The Intel HSF was already starting to breath pretty hard at this voltage and still had a bit of whine and air noise.

C) 5V Fan Results
Heatsink
idle
load
°C rise
°C/W MP
°C/W TDP
Alpha 8952 w/ stock fan
28°C
62°C
40
0.53
0.60
Alpha 8952 w/ Panaflo L1A
30°C
63°C
41
0.55
0.62
Zalman 7000
26°C
45°C
23
0.33
0.35
Stock Intel HSF
28°C
64°C
42
0.60
0.63

At 5V the stock 8952 fan just barely cooled enough but was very quiet. There was just the slightest bit of air noise and no discernible clicking at all. No noise could be heard at all from over one meter away. Switching from the Sanyo Denki fan to the Panaflo at 5V was a wash. Both fans cooled equally and were basically silent. The Panaflo did have a bit more clicking noise than the 8952 fan but you had to get within 6-12" before you could begin to notice it.

Of course the good 'ol Zalman was still working just fine down at 5V. Its cooling performance was still very good and it's noise level was very quiet. I could barely hear any wind noise and just the slightest bit of very quiet clicking from about .5-1 meter away.

The Intel HSF is marginal at 5V. Load temps were starting to get high and its whine and hum were louder than any of the other fans in this test.

WITH A HIGHER POWER CPU?

Alpha claims that their new S-PAL8952 will cool the Intel Prescott, Northwood and Extreme Edition processors but I only tested it with the (relatively) moderate output of the 2.4C processor. We can however, use the °C/W numbers to extrapolate the theoretical performance of the 8952 with any other P4 processor, including the 100+ watt P4 3.4GHz Prescott. According to Intel's "TDP" specs, the 3.4 Prescott puts out 103W. The higher "MP" power rating for the 3.4Ghz Prescott is 115 watts so we'll use those numbers to calculate the estimated maximum CPU temperature for a 3.4E running 2xCPUBurn. The fan used for these calculations is the included Sanyo Denki :

Extrapolated S-PAL8952M82 temps for a 103W, 3.4GHz Prescott using the "TDP" power rating

Fan Voltage
C/W
°C rise
load
12 volts
0.29
30
52°C
7 volts
0.42
44
66°C
5 volts
0.60
62
84°C

Extrapolated S-PAL8952M82 temps for a 115W, 3.4GHz Prescott using the "MP" power rating

Fan Voltage
C/W
°C rise
load
12 volts
0.25
29
51°C
7 volts
0.37
43
65C
5 volts
0.53
61
83°C

Depending on how much faith you have in these calculations, it does look like the S-PAL8952 with its quiet fan can sufficiently cool the hottest running Prescott, at least at 12V. At 7V I would call the performance barely acceptable. Inside a case with minimum >10°C higher ambient temps, it probably would not do.

Would this Prescott cooling performance be acceptable to quiet PC enthusiasts? In my opinion, even at the fan at 12V, barely. The results wouldn't change much if we switched to the Panaflo fan because it's performance is virtually identical to the Sanyo Denki fan.



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