mattius92 :
Actually, the quad core is not advisable at this time, Intel doesnt list it on the compatible list a products for the chipset. Buying it would be a gamble if it actually works. So far the best you can get that is actually listed as compatible is the Core 2 Duo E6700.
The question of the thread is CPU compatibility, basically, and finally I have complete answer on contrary with most existing here, except by short mention by bambiboom.
Dimension 9100 processor upgrade options.
First of all this is the list from an old post. This list contains D9100 processors offered by Dell as an upgrade (that was a long time ago).
Pentium 4
W8404 Prescott P4, 650, 3.4G, 800FSB, 2MB, Socket-T, Mainstream
T7281 Prescott P4, 530, 3.0G, 800FSB, 1MB, Socket-T, E0, Mainstream
W8406 Prescott P4, 670, 3.8G, 800FSB, 2MB, Socket-T, Performance
K8083 Prescott P4 Kit, 64bit, 3.2G, 800FSB, 1MB, Socket-T, E0
YC554 Prescott P4 Kit, 64bit, 3.4G, 800FSB, 1MB, Socket-T, E0
K8087 Prescott P4 Kit, 64bit, 3.8G, 800FSB, 1MB, Socket-T, E0
P8072 Prescott P4 Kit, 520, 2.8G, 800FSB, 1MB, Socket-T, E0
K8085 Prescott P4 Kit, 64bit, 3.6G, 800FSB, 1MB, Socket-T, E0
DD517 Prescott P4 64bit Kit, 521, 2.8G, 800FSB, 1MB, Socket-T, E0, Mainstream
R8419 Prescott P4 Kit, 530, 3.0G, 800FSB, 1MB, Socket-T, E0
W9854 Prescott P4 Kit, 630, 3.0G, 800FSB, 2MB, Socket-T, Mainstream
P7959 PRC, 80547, PENTIUM 4 PRESCOTT DT, 3.6, SKT-T, 64, E0
FC756 Prescott P4 64bit, 531, 3.0G, 800FSB, 1MB, Socket-T, E0, Mainstream
FC754 Prescott P4 64bit, 521, 2.8G, 800FSB, 1MB, Socket-T, E0, Mainstream
W6580 Prescott Extreme Edition P4, 3.73G, 1066FSB, 2MB, Socket-T
U7893 PRC, 80547, PENTIUM 4 PRESCOTT DT, 3.8, SKT-T, 64, E0
P7957 PRC, 80547, PENTIUM 4 PRESCOTT DT, 3.2, SKT-T, 64, E0
P8110 Prescott Extreme Edition P4 Kit, 3.73G, 1066FSB, 2MB, Socket-T
W9856 Prescott P4 Kit, 650, 3.4G, 800FSB, 2MB, Socket-T, Mainstream
W9857 Prescott P4 Kit, 660, 3.6G, 800FSB, 2MB, Socket-T, Performance
FC071 Prescott P4 Kit, 670, 3.8G, 800FSB, 2MB, Socket-T, Performance
P7958 PRC, 80547, PENTIUM 4 PRESCOTT DT, 3.4, SKT-T, 64, E0
W9855 Prescott P4 Kit, 640, 3.2G, 800FSB, 2MB, Socket-T, Mainstream
DD518 Prescott P4 64bit Kit, 531, 3.0G, 800FSB, 1MB, Socket-T, E0, Mainstream
W8405 Prescott P4, 660, 3.6G, 800FSB, 2MB, Socket-T, Performance
W8403 Prescott P4, 640, 3.2G, 800FSB, 2MB, Socket-T, Mainstream
T7280 Prescott P4, 520, 2.8G, 800FSB, 1MB, Socket-T, E0, Mainstream
W8400 Prescott P4, 630, 3.0G, 800FSB, 2MB, Socket-T, Mainstream
Pentium D
KC796 Smithfield P4 Kit, 840, 3.2G, 800FSB, 2MB, Socket-T, Mainstream
W9446 Smithfield P4, 840, 3.2G, 800FSB, 2MB, Socket-T, Mainstream
KC795 Smithfield P4 Kit, 830, 3.0G, 800FSB, 2MB, Socket-T, Mainstream
W9445 Smithfield P4, 830, 3.0G, 800FSB, 2MB, Socket-T, Mainstream
W9441 Smithfield P4, 820, 2.8G, 800FSB, 2MB, Socket-T, Mainstream
KC794 Smithfield P4 Kit, 820, 2.8G, 800FSB, 2MB, Socket-T, Mainstream
After searching through the posts I found that Pentium D 945, 950 and 960 will work as well as tried by users and multiple posts verify this, latest BIOS is required.
Q: What's the difference between the Pentium D 945 and 950 + 960?
A: 945 is 95 watts and 950 and 960 is 130 watts. Also, the 950 and 960 has Intel Virtualization Technology (VT-x).
1) PD945 offers the best performance/price ratio. Its performance is same as 950 and just 5-6% slower than 960.
2) PD945, 950 and 960 all share the same Netburst technology, same bus speed, and same cache of 4MB. The 945 does not support virtualization. The only performance edge 960 has over 945 is its higher clock (3.6 GHz versus 3.4 GHz) which roughly translates into 5% faster performance. No real world difference.
Prior to upgrading the processor, you need to upgrade the BIOS to to the latest version, A03, when support for newer processors was added.
BIOS A03 shows
Fixes & Enhancements
1. Improve keyboard parser buffer operation.
2. Allow USB Controller to be disabled.
3. Improve support for bootable optical drives.
4. Add new Service Tag editing feature.
5. Add support for VIIV logos.
6. Add PCI and Sigmatel support for for Vista.
7. Update the Copyright to 2006.
8. Add support for newer processors. Meaning Pentium D 945, 950 and 960.
9. Improve S3 operation.
10.Improve PME functionality.
11.Correct size reporting in setup.
12.Improve PCIE detection algorithm.
13.Correct USB detach performance.
14.Improve stability when no boot device is present.
The 9100 does not support any Intel Core 2 Duo, or Core 2 Quad processors.
The Core 2 Duo CPU, require a different motherboard, that's the reason for the Dell Dimension 9200 system.
Apparently the Core processors are not compatible with the 9100 even though they seem to be pretty close. The problem is apparently the voltage regulator (and possibly in the BIOS if the board is not designed for the Core).
The 9100/9150 motherboards were designed before the Core2 architecture chips came out and those Core2 chips use different (lower) CPU voltages and the CPU voltage adjusts according to performance demands. The 9200 has the required regulator, but the 9100/9150 do not.
Core 2 uses a new VRM(Voltage regulator module), I think VRM7 or VRD11, while current motherboards (in all dells) use VRM6 (I could be wrong in details here).
Intel website shows that all i945 chipset motherboards are compatible with Core 2 Duo - Dell mobo's are proprietary and built by Foxconn, not Intel. VRM's are managed by system BIOS written by Dell.
Next is possible solution to crack Dell BIOS, however it is just for BIOS, not for voltage, so most likely you will burn your motherboard with new processor eventually, I would not support this way or explain any further as it becoming very complicated even for advanced users.
This is quote from Dell forum thread about 4-5 years ago.
The 9100 doesn't support Conroe. The microcode is not in the BIOS.
Seeing that Dell will never update some BIOSes again, I'll tell you this. You can replace/update CPU microcode in the BIOS yourself with the microcode for the CPU you want to use. For example, to add support for the E6700 processor, you'd take one of the three "cpu0001067a_plat000000**_ver00000a0b_date20100928.bin" files (** is a0, 11 or 44 from the latest Intel microcode.dat). Open the BIOS.hdr (not the BIOS.exe) in a hex editor like HxD. Copy all the text from the new cpu.bin microcode file apart from the first 48 characters (bytes 49-8192) and replace any one of the existing 8 KB CPU microcodes in the BIOS with the new microcode. Update the existing index to "7A 06 01 00 ## ## ## ## 52 45 41 48" (## is the pointer to the actual microcode, so leave it as is). You also need to fix a CRC32 or two (fakecrc in cmdpack works pretty well) and then flash the gzipped BIOS.hdr by booting to FreeDOS or stuff the .hdr to the .exe and run it in Windows.
http://en.community.dell.com/support-forums/desktop/f/3514/p/19327747/19678802.aspx#19678802
Story of failure, would you want to join those failed users?
I read two success stories about installing a E6600 in a Dimension 9100. I have a Dimension 9100 with a prescot and I am turning it into a media server and home theater PC. I upgraded to A03 and I tried with a E6600 from a friend. My 9100 did not POST and had a steady amber light in the power button with the E6600 in it (according to Dell support is an unsupported CPU or other unsupported hardware)
http://en.community.dell.com/support-forums/desktop/f/3514/p/19327747/19678802.aspx#19678802
At the end, just want to add another Tom’s discussion which included delluser1 responses – this user seems to know great deal about Dells, I seen his posts before many times, and he/she was right on target
http://www.tomshardware.com/forum/254277-31-upgrading-dell-dimension
The question is answered, now is the question - is it worth the headache, upgrade to 960 will require checking for cooling options as well duet to high, 130 watt TGP of processor.