The Dell Dimension 2350 Desktop PC motherboard, has an Intel 845GL motherboard chipset,
mounted to it. (System Information),http://support.dell.com/support/edocs/systems/dim2350/specs.htm#1101572
Here we see that the Intel 845GL chipset supports processors, with a -> maximum <- Front Side Bus of 400MegaHertz, (FSB = 400MHz max.),http://en.wikipedia.org/wiki/List_of_intel_chipsets#Pentium_4_chipsets
The Intel Pentium 4 model 530 (3.0GHz. Also has Hyper-threading Technology. HT), operates with a FSB of 800MegaHertz, (FSB = 800MHz),http://en.wikipedia.org/wiki/List_of_Intel_Pentium_4_microprocessors#Prescott_.2890.C2.A0nm.29_2
(Scroll down. Pentium 4 HT 530 )
You can't make the Intel 845GL chipset support a processor with an 800MHz FSB.
BIOS update or not, the voltage range will be too low. Therefore the FSB is low. Changing just the Multiplier will not do the trick either.
(BIOS Setup, Advanced Chipset Setup. Doubt the options of changing the FSB, and/or Voltage, and/or Multiplier, is available with that BIOS program))
Note your 3.0GHz processor is operating at 1.5GHz?
Max FSB supported is 400MHz, and your Model 530 needs 800MHz? (For max operation)
Post additional questions in a Comment.
[ Chip and Chipset are shortened terms for I.C.
The motherboard chipset technology used for your computer, has a Northbridge chip, and a Southbridge chip.
(Does not apply to motherboards that support the Intel Core i3, Core i5, Core i7, and Core i9 processors )
The Northbridge chip handles the faster capabilities of a computer.
Processor, Ram Memory, and High-speed graphics.
[ The AGP technology, and the PCI-Express technology, is High-speed graphics.
Using a graphics card in a PCI slot, or using Integrated Graphics, is NOT High-speed graphics ]
The Southbridge chip handles the slower capabilities of a computer.
Anything connected to the PCI bus, (Such as a PCI graphics card)
[ CPU stands for Central Processing Unit. Another term used is Microprocessor, or Processor for short ]
So it is first up to the Northbridge chip, of the motherboard chipset, whether it will support a certain processor, THEN if a BIOS update will help.