Dell Precision 390 , Which CPUs work for an upgrade?

The best place to start looking for processor upgrade compatibility is Intel's site for the chipset:
http://ark.intel.com/products/chipsets/22688

Not all of these may be supported by the Dell BIOS, but processors not on this list will NOT be supported at all.

As you can see, the Intel 975X chipset in the Precision 390 supports various single-core P4's, the Pentium D 830, and various Core 2 processors (including the Q6600).  Dell's documentation lists support for "select" Core 2 Duo processors.  This either means that they did not update their docs once Quads came out (they do not update their docs but usually issue an "Information Update", which none is available for the 390) or they are indeed not supported by the Dell BIOS.  If you can get a listing from Dell support of the processors/part numbers that are supported, that should give you an idea of how much of that chipset processor list can be considered for a processor upgrade.

Before attempting any CPU upgrade, update the BIOS, as it will add code to support various processors - if they are supported at all.

I got the info from Dell today. There are two motherboards used in the 390. One supports the Cedar Mill and Conroe line of CPU's. The other motherboard for the 390 supports the Q6600, QX6700 and QX6800.

Each time I contact Dell I get the same evasive answers. Never an exact answer with the Model Number and exact Part Numbers, only generic, Yes and polite No

Which motherboard model number supports which cpu ??????

I just purchased a used Dell Precision 390 with the Core 2 Quad-Core Extreme QX6700 (Kentsfield), with a i975X chipset.

And excluding the vernaciular of the cpu description, it means I have four cpu's on a Core 2 processor... that makes sense, right?

I still get confussed looking up the specs.

(ohhh... and to rub it in even further, I only paid $90.00 for the rig)

The heatsink is apparently the largest one they used for this model.

The Dell motherboard is listed as a 0DN075, as per CPUID.

And you are correct in your assumption that there are at least three different mobos that support only certain chips.

Which basically means, y'all can't cross-upgrade to the next/improved line of CPU's if'n your mobo don't support it.

I can only suggest you actually use your Mark I Eyeball and confirm the cpu model by removing the heatsink and thermal compound, and then Google search the cpu and your motherboard model.

After that, you'll be able to determine the maximum upgrade that's possible for your rig.

Cheers!

 I can confirm that a Dell 390 that has a Cedar Mill CPU in it, will not support a Q6600 but will accept a E6300. I changed one Dell 390 with a Cedar Mill P4 in it to a E6300 with no problems. I tried a Q6600 in it and it does not see all of the cores.This is my personal experience.

Now, Here's some more info I gleaned from the web:

The precision 390 shipped with 2 different motherboards. One for the Cedar Mill and Conroe CPU's, and one for the Kentsfield CPUs. the Kentsfiled are the quad core Q series, the E6xxx and E4xxx are the conroe series.

Depending on the part number of the motherboard it may not work with the Q series processors.

I Googled for Precision 390 and found Dell shipped these machines with Q6600, Q6700, QX6600 and QX6600 processors.

My guess you could use any core 2 duo or core 2 quad 65nm CPU with a 1066 FB.

There are 2 revisions of the board A00 and A01. The revs had nothing to do with CPU support though. The 975x chipset although not clearly documented supports some Quad CPU's. Tough to read through all the 975x technical specs on Intel's site.

Dell is not about upgrading old machines they are about selling you a new one so they are no help.

Honestly, as long they keep providing the specs of the older machines I am good with that.

Upgrade your BIOS to the latest version and pickup a Q6600, Q6700, QX6600 or QX6600 CPU.

I added 2 GB of RAM for a total of 4 GB (XP sees only about 3.5GB of it), a Q6600 and 1 TB Drive for 250.00. Small investment without having to mod a thing. The only thing I can't squeeze any more performance out of is the on board disk SATA controller.

The only concern I had is the Q66xx CPU's can use up to 105 watts. The e6320 that was originally installed was a 65 watt processor. I used Intel's TAT (Intel Thermal Analysis Tool) Google to find and I maxed the Q6600 CPU to 100%. It ran warm with the stock Dell cooler but not HOT.

I optimized the machine for Pro Tools 8.04 with a Mbox Pro II Firewire interface and it rips right along.

I hope this helps,

Plexz

Can you verify if this works with QX6800 (quad core)  not the dual core X6800...  my board in ODN075 and I am running on intel Q6600.  As dell boards cannot overclock I plan to change the processor with the extreme version qx6800.

anybody using QX6800 with precision 390?  Thanks in advance.

ho update bios plz i have dell presicion 390