This is not determined by the Model number of Dell.

Unless its a Pentium D or Core2 Duo processor its likely that its 32 bit.

It will show EMT64 capable or not in the F2 Bios settings under Processor Features.

I have a Dell Dimension 9150 desktop.  Does this machine have a 32 bit processor or a 64 bit processor?

Most likely, it's 64-bit.

The 9150 was produced around 2005 and that was just before the Core 2 duo CPUs were released.None of Intel's earlier CPUs (Core Duo, Pentium M, Celeron M, Pentium 4) implements EMT64

The following processors implement the Intel 64 architecture:

    NetBurst microarchitecture
        Xeon (all models since "Nocona")
        Celeron (some models after "Prescott REV E0")
        Pentium 4 (some models after "Prescott Rev E0")
        Pentium D
        Pentium Extreme Edition
    Core microarchitecture
        Xeon (all models since "Woodcrest")
        Core 2 (including Mobile processors since "Merom")
        Pentium Dual-Core (E2140, E2160, E2180, E2200, E2220, E5200, E5300, E5400, E6300, E6500, T2310, T2330, T2370, T2390, T3200 and T3400)
        Celeron (Celeron 4x0; Celeron M 5xx; E3200, E3300, E3400)

ALL of the CORE DUO vs CORE2 DUO were 32 bit.

Unless its Penitum D or Core2 Duo it likely has a 32 bit Pentium 4 but this can be F2 verified in Bios as to whether

EMT64 is available or not under CPU features.

November, 2005
Intel® Pentium® 4 Processor 662 and 672
3.6 - 3.8 GHz

February, 2006
Intel® Core™ Duo Processor T2050/2250/2350/2450
1.6/1.73/1.86/2.0 GHz


January, 2006
Intel® Pentium® D Processor 900
2.8 - 3.4 GHz

 

July, 2007
Intel® Core™2 Extreme quad-core QX6850
2.66-3.0 GHz

Intel® Core™2 Quad Q6700
2.66 GHz

Intel® Core™2 Duo E6550-E6850
2.33-3.0 GHz

Mobile Intel® Core™2 Extreme X7800
2.6GHz

Intel® Core™2 Duo Processor T7200/T7400/T7600
2.0 GHz
2.16 GHz
2.33 GHz

The 9150 was produced around 2005 and that was just before the Core 2 duo CPUs were released.None of Intel's earlier CPUs (Core Duo, Pentium M, Celeron M, Pentium 4) implements EMT64

Intel had moved to 64-bit before the Core 2 series.

All the pre-Core 2 Dell 775s I have are 64-bit compatible. They include a GX620, OptiPlex 320, and Dimension 3100. My relative's 5150 is 64-bit-compatible, too.

I think's it's highly likely the CPU the OP is asking about is 64-bit-compatible, too, but you're right, it should be checked in the BIOS.

They had but there weren't early prescott cpus that had the feature.  X64 started in the XEON line before Pentium 4 desktop line.  There are 300 models before X64 and 29 that have x64

Aka 90 percent DO NOT have X64.  Can be F2 verified in bios.

This is also why the max ram is 4 gigs.

Later Systems Like the Optiplex 745 and 755 can use 8 gigs of ram.

Wasn't until after the Rev E0 prescott's that X64 was introduced.

The 570J for example DOES NOT support X64

http://ark.intel.com/products/27475/

The 571(SL7P2)introduced 3rd QTR 2005 does.

http://ark.intel.com/de/products/27476/Intel-Pentium-4-Processor-571-supporting-HT-Technology-1M-Cache-3_80-GHz-800-MHz-FSB

Socket type	Socket 775 (LGA775)
CPUID	0F41h
Core stepping	E0
Processor core	Prescott

Willamette  Nov 2000
Northwood   Jan 2002
Prescott    Mar 2004
Prescott XE Feb 2005
Cedar Mill  Jan 2006

final revision of the Pentium 4 was Cedar Mill, released on January 5, 2006

Pentium 4 800Mhz FSB Socket T with HT, XD, EM64T, 2MB L2 cache and EIST (6XX)series

Pentium D (8XX) Series.

DDR2 8 gigs is common and easy on Optiplex 745's and 755's

Here is a user that is NOT able to get 2x 2 gig working in a 9150

http://en.community.dell.com/support-forums/desktop/f/3514/p/19500497/20343229.aspx

E310's also came with 2.8ghz SL7KH 32 bit prescott's most commonly.

The most common 2.8ghz p4's were 533mhz 1 meg prescotts which are NOT Emt64 compatible.

It is completely disingenuous to say that All prescotts support EMT64 especially PRE Rev E0.

Family    Intel Pentium 4
Processor number       510
Part number    B80547PE0721M
BX80547PE2800ET
Frequency (GHz)       2.8
Bus speed (MHz)       533
Clock multiplier       21
Socket type    Socket 775 (LGA775)
CPUID    0F34h
Core stepping    D0
Processor core    Prescott
Manufacturing technology (micron)    0.09
L2 cache size (MB)       1
Core voltage (V)      1.25 - 1.4
Case temperature (°C)       67.7

http://ark.intel.com/products/27445/Intel-Pentium-4-Processor-2_80-GHz-1M-Cache-533-MHz-FSB

 The first digit, or the prefix letters and the first digit in the processor number,
can be used to identify Intel processor family:

 
    4xx - Celeron
    5xx - Pentium 4  Many not X64 compatable
    6xx - Pentium 4
    8xx - Pentium D and Pentium Extreme Edition
    9xx - Pentium D and Pentium Extreme Edition
    E1xxx - Celeron Dual-Core
    E2xxx - Pentium Dual-Core
    E3x00 - Celeron Dual-Core
    E4xxx - Core 2 Duo
    E5x00 - Pentium Dual-Core
    E6xxx - Core 2 Duo
    E6x00 - Pentium Dual-Core
    E7x00 - Core 2 Duo
    E8xxx - Core 2 Duo
    G6xxx - Pentium Dual-Core

 

Statistically speaking the odds are that it is NOT x64 compatible.   Which is why I made the 570 Prescott reference. 

When they started supporting 8 gigs of ram and core2 duo it made more sense to support X64. F2 Definitely will tell without having to open the case and look or run software.

We went thru this with Our Optiplex 620's over 5000 of them.  More than 75 percent had SL7KH

http://ark.intel.com/products/27445/Intel-Pentium-4-Processor-2_80-GHz-1M-Cache-533-MHz-FSB

533mhz Prescotts.  These were VERY common in many Dell models including the 620 and XPS400.

Only the High end versions had Pentium D 800 series.  Some wanted to keep their system so we upgraded towers to Pentium D 960's and the heatsinks and updated them to PCI-E video and 4 gigs of ram.  The rest were surplused and Optiplex 755's thru 780's were purchased a few at a time to replace them.  Now everyone wants 64 bit windows 7 and 8 gigs of ram with Radeon 7750 because they see what a nice machine they are when they get that update.

 

It is completely disingenuous to say that All prescotts support EMT64 especially PRE Rev E0.

I didn't say that, just that Intel CPUs were all 64-bit by the time the Core 2s were released.

By the time the Core 2 series was introduced, all of Intel's CPUs were 64-bit-compatible. My pre-Core 2 OptiPlex 320 has a Celeron CPU, and even it is 64-bit-compatible. My 3100 has the most common CPU available in the model, a 2.8ghz P4, and it is 64-bit-compatible.

8gb of RAM didn't become popular until DDR3 became available. With DDR2, 4gb was a premium configuration; in 2006, 2gb was premium.