Overheating problem with Dell Poweredge 400SC P4 2.8

I bought a PE 400SC Pentium 4 2.8 GHz machine and it is really great.  I use it for my business and it serves me well.  Recently, for maybe the past two weeks or so, I have noticed that the temperatures of the CPU running at 100% usage have been somewhat high.

 

I am using Motherboard Monitor 5.3.7.0 with a motherboard setting of Intel  D875PBZ.

 

Here is what I have been getting:

 

100% CPU usage (running 2 Folding@Home cores in Hyperthreading mode) - 149 F or 65 C

 

I thought this was high, so I checked the fans, heatsink, and other components and everything seemed fine.  I used to get 138 F before when I first got the computer.

 

My computer is on 24/7/365 and it is always running Folding@Home clients.

 

Today, it was especially hot in my office and I thought I would take action and opened up the machine and removed the heatsink, scraped off the thermal tape, and applied some good quality Arctic Silver thermal paste to the CPU.  I followed their procedure and was careful not to contaminate the two surface. In any case, I put the system back together and now the temperature at 100% load is hovering around the 159 to 160 F range.

 

I went up almost 10 F since yesterday and about 20 F since I got the computer in July. 

 

I removed the Artic Silver and redid it, just to make sure.  Still no difference.  Usually when I apply Arctic Silver to a CPU, it lowers the temperature about 5-7 deg. C. 

 

One more thing I noticed.  The fan on my machine that pulls air through that green shroud is not running "hard" like it used to before when my room got hot and the CPU temps went above 140 F.  It is stays pretty silent.  Now, I see that the fan has a thermocouple on the exit.  So it measure how hot the air is coming out of the system, and increases the fan speed based on that.  If the CPU is getting too hot, it will heat up the air in the shroud, the fan sensor will pick that up, and increas the RPMs on the fan to compensate.  My fan is not really doing that all too well.  I don't think it is a fan defect either.  It seems for some reason, the CPU is getting hot but the heat sink on top is not conducting heat properly away.  This would only happen for one reason - the CPU/heatsink interface is poor and the CPUs heat is not being carried away by the heatsink properly.

 

But I thought applying ArticSilver should have solved that. 

 

What to do?  Any thoughts and suggestions are welcome.

 

BTW, this computer is only two months old and it is still under warranty, so if you Dell moderators read my post, please let me know what I can do. I much rather fix the problem myself and in the process learn about about fixing my computer, but if I can't get my temps down below 138 F at 100% CPU usage, I might have to have my computer serviced.

 

Thanks,

 

Pradeep