Can pc2100 memory work with a 533 bus processor?

[dterrors]

I'm building a PC and it won't post, nothing on the screen. Actually,
I'm replacing motherboard/processor of a working PC. So that narrows
things down... All the other parts are presumable in working order, or
were 24 hrs ago, only proc and mobo are new. I've reset cmos, I've
taken out PCI cards, disconnected IDE and floppy so there's no hd,
simplified the system, still won't go.

So here's what I don't get about bus speed/processor/memory. The
motherboard says it can take pc2100 ddr dimms, and that's what I've got
plugged into it (I even tried take one out at a time to see if one was
the problem). The processor I'm trying to use is a Celeron D 3Ghz,
which runs at something like 533 bus. So is the processor
incompadible with the memory? Can't the processor like slow down to
the memory's speed, at least enough for it to post?

I know it's not *optimal* to run with slower memory than the proc could
use, but isn't it supposed to work enough to at least get into bios?

 

[Dave]

I'm building a PC and it won't post, nothing on the screen. Actually,
I'm replacing motherboard/processor of a working PC. So that narrows
things down... All the other parts are presumable in working order, or
were 24 hrs ago, only proc and mobo are new. I've reset cmos, I've
taken out PCI cards, disconnected IDE and floppy so there's no hd,
simplified the system, still won't go.

So here's what I don't get about bus speed/processor/memory. The
motherboard says it can take pc2100 ddr dimms, and that's what I've got
plugged into it (I even tried take one out at a time to see if one was
the problem). The processor I'm trying to use is a Celeron D 3Ghz,
which runs at something like 533 bus. So is the processor
incompadible with the memory? Can't the processor like slow down to
the memory's speed, at least enough for it to post?

I know it's not *optimal* to run with slower memory than the proc could
use, but isn't it supposed to work enough to at least get into bios?

You are confused. Modern processors are significantly faster than RAM runs
at. No matter what your processor speed is, and no matter what your RAM
speed is, the CPU won't communicate with the RAM at all.

The only reason a mainboard can POST and run OK is that the mainboard has a
chipset. The chipset acts as a buffer/translator between the CPU and RAM.

Now let's look at your specific system. Your Processor is clocked at 533MHz
(times some multiplier, maybe 5.5?, assuming that the real speed is 3GHz).
Your RAM is clocked at 133MHz (aka DDR266 aka PC2100). A CPU running at
533Mhz FSB is NOT going to communicate with 133MHz RAM, without help.

Luckily, it has the mainboard chipset to enable free communication between
CPU and RAM. So what does the mainboard manufacturer have to say about the
CPU and RAM? Does the mainboard support your CPU? Does the mainboard
support your RAM? If the answer to both is "yes" (most likely), then . . .

Then your CPU and RAM are perfectly compatible, when both are installed on
your mainboard.

So we should be focused on the real problem, which would appear to be that
your computer won't POST. There are three components needed for the system
to POST:
Power supply (must be compatible with all components, and strong enough to
run them!!!)
Mainboard
CPU

You've just replaced mainboard and CPU, which makes them very likely
suspects, as far as what, if anything, might be defective.

HOWEVER, you also need to consider whether your old power supply is
supplying enough juice to allow the mainboard and CPU to operate. If your
system is typical, then a 300-350W power supply will suffice, if it is a
good name brand. If you don't KNOW if your power supply meets these
specifications without checking, then you might have a weak power supply.

But the most likely explanation for what you are seeing is that you've
probably hooked something up wrong. (check, double-check and triple-check
ALL cables . . . if they all look good, yank them all off and start over).
The second most likely explanation is that your mainboard might be
defective. There is a slim possibility that your CPU might be defective, or
need to be reseated. But that's a long-shot.

Good luck, -Dave