ehsanelahi,
Yes, You may change a Dell Precision T3500 to an Intel i7 of the 9XX variety.
An easy way to find out this information is to discover from the specifications sheet >
http://www.dell.com/downloads/global/products/precn/en/q2wk6_dell_precision_t3500_spec_sheet.pdfhttp://www.dell.com/downloads/global/products/precn/en/q2wk6_dell_precision_t3500_spec_sheet.pdf
> that the T3500 uses the Intel X58 chipset, supporting Xeon 5600-series, then go to the Intel ARK site and select "Compatible Products". See>
http://ark.intel.com/products/36785/Intel-X58-Express-IO-Hub#@compatibility
Which lists all the CPU's that work with the X58.
As for i7's, the situation is complicated as I've not been able to find a used T3500 with an i7. Doing a search for "Dell Precision T3500 i7" produces a number of results, but checking in detail, they are all actually W-series Xeons.
My thought is that it may depends on the ability to use ECC RAM.
Still, there are some good options. If you're on a budget, the Xeon W3570 four core is still a respectable 3.2 / 3.46GHz and seems to sell for around $90-120. (7.14.)
The Xeon W3580, 4 core 3.33 /3.6 about $140-180.
It's a pity if i7's don't work as a quick look on Ebay at the fastest i7 CPU's for the X58- is the i7 990X, (Extreme) 6-core /12 thread @ 3.46 / 3.73GHz. It scores 8808 on Passmark at No. 57- still fast by current standards. There don't seem to be any 6-core Xeons for the X58. The i7 990X appears to be in the $400-600 range on Ebay.
Still a good number of options. As you have 4 systems, you can of course, make one an F1 racer, then a couple of sport coupe, and a station wagon for example for 2D.
Dell Precisions are excellent systems- beautifully made and ultra-reliable. The TX500 series was an excellent one- very good performance. I was very near to buying a used T7500 with the outstanding 6-core X5680, but I got a very good price on a new Z420 I didn't buy the T7500. I still use my 2008 T5400 though to sit in the corner and render.
Cheers,
BambiBoom
HP z420 (2014) > Xeon E5-1620 quad core @ 3.6 / 3.8GHz > 24GB ECC 1600 RAM > Quadro 4000 (2GB)> Samsung 840 SSD 250GB /Western Digital Black WD1003FZEX 1TB> M-Audio 192 sound card > AE3000 USB WiFi > HP 2711X, 27" 1920 X 1080 > Windows 7 Ultimate 64 >[Passmark system rating = 3923, CPU=9139 / 2D= 839 / 3D=2048]
Dell Precision T5400 (2008) > 2X Xeon X5460 quad core @3.16GHz > 16GB ECC 667> Quadro FX 4800 (1.5GB) > WD RE4 500GB / Seagate Barracuda 500GB > M-Audio 2496 Sound Card / Linksys 600N WiFi > Windows 7 Ultimate 64-bit >[Passmark system rating = 1859, CPU = 8528 / 2D= 512 / 3D=1097]
2D, 3D CAD, Image Processing, Rendering, Text > Architecture, industrial design, graphic design, written projects