which DDR memory?

[Patrick]

Hello,


I just bought a new motherboard (Chaintech 9VIF1, see specs below) and a 2.5
Ghz Celeron. According to the specs, it takes PC1600 or PC2100 memory. From
what I gather, a PC2100 module corresponds to a 266 MHz bus speed.

However, the specs for this motherboard also indicate that it will take
either an Intel P4/Celeron@400 MHz or a P4/Celeron@533MHz.

It seems to me that the speed of the memory (266MHz) doesn't match the speed
of the CPU (400MHz/533MHz).

Can someone please tell me which memory I need?

Thanks,
Patrick
______________________________


Specifications:
Processor Interface: Socket 478
Processors Supported:
- Intel Celeron @ 400MHz
- Intel Celeron @ 533MHz
- Intel Pentium 4 @ 400MHz
- Intel Pentium 4 @ 533MHz
Chipset:
- VIA P4M266A Northbridge
- VIA VT8235 Southbridge
Front Side Bus:
- 400 MHZ
- 533 MHZ
Memory:
- 2 184-Pin Memory Slots
- 2GB Maximum Memory Supported
- Supports PC1600/2100 DDR SDRAM modules

 

[Tweek]

The P4 bus is 'quad pumped', so if you have a Celeron with a 400Mhz bus, it
is quad pumped to 400Mhz. Your DDR memory is double data rate. PC 1600
memory actually runs at 100Mhz, but because it is DDR, it is effectively
200Mhz. The P4 with a 533 bus is quad pumped 133Mhz, and PC 2100 Memory is
running at 133Mhz, which is effectively 266 DDR, so everything matches up.
It gets more confusing because the memory can actually be run asyncronously
with the bus, so a P4 with an 800Mhz bus (200mhz quad pumped) can still be
used with PC2700 memory (166mhz or DDR333).

 

[~misfit~]

Hello,


I just bought a new motherboard (Chaintech 9VIF1, see specs below)
and a 2.5 Ghz Celeron. According to the specs, it takes PC1600 or
PC2100 memory. From what I gather, a PC2100 module corresponds to a
266 MHz bus speed.

Ok. here's the deal. It's not a 266*MHz* bus speed, it's 133MHz. The 266 or
533 or 800 or 400 or whatever figures are data-rate. The actual MHz rating
is (in your case) either 100MHz (PC1600 RAM) or 133MHz (PC2100 RAM)

However, the specs for this motherboard also indicate that it will
take either an Intel P4/Celeron@400 MHz or a P4/Celeron@533MHz.

This marketing hype pisses me off and casues so much confusion. Those
figures you have above aren't actually MHz ratings, they are data
through-put ratings, using what Intel refers to as "Quad-pumped" The MHz
ratings are, as I've said above, either 100Mhz (Quad-pumped = 400 data rate)
or 133MHz (Quad=pumped (I hate that term) 533 data rate)

It seems to me that the speed of the memory (266MHz) doesn't match.

The memory runs at 133MHz. As it's DDR (Dual-data rate) memory it gets
called 266. It annoys the hell out of me that they have the audacity to put
*MHz* after the figure.

the speed of the CPU (400MHz/533MHz).

*NOT* MHz. That's Intel-speak for 100MHz and 133MHz. Spin doctors and
marketing people have a lot to answer for.

Can someone please tell me which memory I need?

Sure, you need *at least* PC1600 memory for low-end Celerons. However, I'd
use PC2100, PC 2700 or preferably PC3200. PC1600 memory is a dead-end, only
any good for Celerons. The higher rated memory will run at lower speeds
quite happily and allow you head-room for faster memory timings and the
option to upgrade to a faster Celeron or P4 at a later date if you so
desire, without having to change your memeory modules.

It is increasingly hard to get PC1600 memory and some outfits don't even
stock it anymore, or if they do, they charge more for it. This is because
it's not very common and faster memory is backwards-compatible. It sells
faster so they can afford to have lower margins. My supplier doesn't stock
anything slower than PC3200 anymore.

My suggestion would be to buy at least PC2100 memory, for the reasons given
above, or faster if there isn't too great a price difference.

Thanks,
Patrick

No problem.

Specifications:
Processor Interface: Socket 478
Processors Supported:
- Intel Celeron @ 400MHz
- Intel Celeron @ 533MHz
- Intel Pentium 4 @ 400MHz
- Intel Pentium 4 @ 533MHz
Chipset:
- VIA P4M266A Northbridge
- VIA VT8235 Southbridge
Front Side Bus:
- 400 MHZ
- 533 MHZ

Grrr! That should read: 100Mhz or 133MHz FSB. Or 400/533 data rate.

Memory:
- 2 184-Pin Memory Slots
- 2GB Maximum Memory Supported

- Supports PC1600/2100 DDR SDRAM modules

And higher. Don't let the marketers confuse you.

Good luck, I hope that helps.

 

[jasmith]

This is really confusing. The best thing to do is buy Scott Mueller's latest
book and read w/he has to say about the way things work in a computer. The
"speed" of your memory is controlled by what your mb says. You can go to a
faster speed than what it says, but you might be wasting $$ because the
memory will be regulated by the mb.
You would never be able to quad pump a celery and if you want to be running
800FSB you better have one of the top MBAs and have a P4-2.4C,2.8C , or
something that will run @ 800FSB,or so, that's the way I understand it.