Can dual core processors only use one core?

If you're asking if you can put a dual core processor into you motherboard and it'll only run single core, then I seriously doubt it.

Any motherboard that can accept a dual core CPU, will be able to run it. If your motherboard can only run a single core, then it probably pre-dates when multi-core hit the mainstream.

Tough call! The best information I can find indicates that your system packs the Intel® D915G chipset, meaning that it was designed for the Pentium Processor® 4™ and Pentium Processor® D™ (FCLGA 775) and will not run the later Core2™ CPUs, which require the 40-Series chipsets. If the Pentium Processor® D™ is already a non-booter, I'd put the blame on a BIOS calibrated for one core and not more than two threads.

According to dell spec. the 4700 series has a 915G chip set with a Pentium 4 CPU That's NOT a single core (like an older Celeron) but we need more info for the correct answer.

If the chip will fit in your CPU socket, but not run correctly then check to see if there is a BIOS upgrade for your motherboard that might include dual core support. That being said, even that newer CPU is very old now and a modern entry level system would probably kick it's ***.

I said, get a new(er) proc from AMD, they have great/good x3, and x4 procs for pretty cheap. If you still want dual core and you like intel go with the i3.

Good AMD x3 procs:

Phenom II x3 720 - 104$ on newegg

Good CHEAP AMD x4 procs:

Phenom II x4 810 - 134$ on Newegg

Phenom II x4 940 - 155$ on Newegg if you want the Cooler, if not its 140$

Phenom II x4 945 - 150-164$ On Newegg depending on what features you want.

Or if you have some money and you dont mind spending it pick the i5 or the i7.

yes