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Old 03-14-2006, 02:14 PM   #1 (permalink)
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Join Date: Mar 2006
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Exclamation CPU Overheating?? Video Card/PSU Upgrade: Help!!


I have a Dell which came equipped with a standard 250 watt power supply and a Nvidia 5200 Graphics Card. Everything was fine with this setup until I decided to upgrade my Video Card to an ATI x850 Pro. As everyone knows by now, the standard dell PSU simply can't handle newer, power hungry cards. I purchased a 420w thermaltake power supply on recommendation from someone who made the same replacement himself on a 4600.

Oddly, I noticed absolutely no difference in performance after installing my new Power Supply. Performance was still sluggish and I was very perplexed. Until today. Something happened which may turn out to be the beginning of a solution.

My case fan has always been and still is extremely quiet, even when a heavy load is placed on the system such as a graphics intensive Applications. One day, however, I was playing such a game for quite a long time and I noticed the case fan had revved up quite dramatically. As the case fan grew louder, the game became faster. Now this has never to me happened before, and the only thing I can imagine is that the CPU was very hot (unfortunately Dell CPU Temps cannot be measured).

I quit to the desktop and observed the fan slowly return to normal speed.

I then placed my hand over the back of the exhaust and felt the case fan speed up, when I removed my hand it returned to normal. I should note at this point the exhaust fan is connected by a housing shroud to the CPU unit itself. I decided to run some benchmark tests to see how the fan speed affected my performance.

Doom 3 Frames-Per-Second Benchmark test (control):

37 FPS

I then performed the exact same benchmark test while covering the exhaust slightly to increase fan speeds:

48 FPS

I then used a piece of duct tape to close off enough of the exhaust pin holes to bring the fan up to near full-speed.

the result: 60 FPS!!

When I returned to the desktop the fan then slowly returned to it's normal operating speed once again. I do not make a habit out of doing this as I know the damage it could cause.

I am very confused by this and would really appreciate some input. I have a feeling that a heatsink with a powerful fan would give the same effect as artificially increasing the exhaust speeds.... My video card temperatures always remain constant even at max operating temperatures, so I know it has nothing to do with the temperature of my Video Card. It must have something to do with the cooling of the CPU as the case fan speeds are directly proportionate to system performance.

As i said I have a feeling that a heatsink with a powerful fan would give the same effect as artificially increasing the exhaust speeds.... Any advice or links would be greatly appreciated.

Thank you so much for taking the time to read this,

Best wishes -

Toby Cole

*note: when I say case fan i am not referring to the Power Supply unit. The case fan is an exhaust which is connected to the CPU by a plastic shroud to eliminate CPU heat.

Operating System Microsoft Windows XP Professional
OS Service Pack Service Pack 1
DirectX (DirectX 9.0c)
Computer Name DELL
User Name pc

CPU Type Intel Pentium 4, 2800 MHz (21 x 133)
Motherboard Name Dell Dimension 4600i
Motherboard Chipset Intel Springdale-G i865G
System Memory 1024 MB (PC2700 DDR SDRAM)
BIOS Type Phoenix (08/26/04)
Communication Port Communications Port (COM1)
Communication Port ECP Printer Port (LPT1)

Video Adapter RADEON X850 Series (256 MB)
3D Accelerator ATI Radeon X850 Pro AGP (R481)
Monitor Dell E172FP [17" LCD] (M160943A0LHS)

Audio Adapter Intel 82801EB ICH5 - AC'97 Audio Controller [A-2/A-3]

IDE Controller Intel(R) 82801EB Ultra ATA Storage Controllers
IDE Controller Intel(R) 82801EB Ultra ATA Storage Controllers
Disk Drive ST340014A (40 GB, 7200 RPM, Ultra-ATA/100)
Optical Drive HL-DT-ST CD-RW GCE-8483B (48x/32x/48x CD-RW)
Optical Drive SAMSUNG DVD-ROM SD-616E (16x/48x DVD-ROM)
SMART Hard Disks Status OK

C: (NTFS) 38138 MB (20527 MB free)

tobycole is offline  
Old 03-14-2006, 04:20 PM   #2 (permalink)
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Join Date: Dec 2004
Posts: 268

Have they tried to do something clever by limiting the speed of the CPU with temp or something daft like that?

Have you mooched around in the BIOS to see if there are any daft Dellish settings being a pain in the arse?

jono199 is offline  
Old 03-14-2006, 04:53 PM   #3 (permalink)
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Join Date: Mar 2006
Posts: 2

You know... that's exactly the kind of foolish thing you'd expect dell to do.

As far as the BIOS settings go, I did take a look at them and made a few changes which had no effect.

Ever since I replaced the old PSU I have not been able to hibernate which lets me know something is amiss. That being said - the computer fan never did rev up before the upgrade either.

I know this computer can run Doom 3 @ 1024x768 on High Quality @ 60 FPS in a timedemo with Norton 2005 running in the background..... that's saying something... I'm not giving up on this rig quite yet.
tobycole is offline  
Old 03-14-2006, 09:04 PM   #4 (permalink)
Wizard Techie
Join Date: Jan 2005
Location: Delaware
Posts: 3,475

I would buy a new fan and hook it up to the PSU for full power (like a panaflo if it will fit - you may have to get a 25mm instead (thickness)).

Dell's fans use proprietary power connectors so the BIOS will pick up a Fan failure everytime you boot which could get annoying.
turtile is offline  
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