This page continues from Page 1 of the Guide to the [Intel
Northwood Pentium 4 CPU].
It's rumored that Intel cut a deal with Rambus, which awarded Intel mega-buck$ if they helped Rambus sell a lot of their RAM (by manufacturing chipsets that require Rambus RAM). I haven't researched these rumors enough to know if they are true, but I do know many people dislike Rambus. For these people, it's a matter of principle not to buy Rambus RAM.
At least one article suggests that Rambus "took unfair advantage of open JEDEC discussions, and patented concepts developed in industry committees." And the courts have recently found Rambus guilty of fraud. Personally, I'm too much of a capitalist to care about the details of techno-ethics. I merely want maximum performance for my buck, with rock-solid stability.
The price of Rambus RAM has dropped dramatically over the last few months, but is still significantly more expensive than DDR RAM, which performs comparatively to (and perhaps even better than) Rambus RAM, due to its lower latency.
You can get an idea of the relative prices of both Rambus & DDR RAM at either Mushkin or Crucial. At time of this writing, a single 256MB stick of non-ECC Mushkin 800MHz Rambus RAM cost $149. Crucial sells its 256MB stick of PC2100 DDR RAM for $88 (free shipping).
I searched Pricewatch and found 256MB sticks of PC800 Samsung Rambus RAM for $95 at New Egg (Cosair) .. better than Mushkin's $129. Others had better prices, but I refuse to purchase anything from a reseller with a poor resellerrating. New Egg's reseller rating is posted here. RJtech had some nice prices, too. Googlegear has Samsung PC800 here.
Note: It seems that the prices of DDR RAM have spiked in the last few weeks, while the prices of Rambus DRAM have remained constant or dropped. I heard that this is due to the increased demand caused by Intel releasing their DDR-enabled chipset. This changes the decision-making dynamics.
Looking at RDRAM-based solutions, the Asus P4T-E motherboard (not to be confused with the 423-pin P4T, without an 'E' on the end), will support Northwood P4 CPUs with a simple BIOS flash upgrade (see info listed under Feature Summary at bottom of the Asus page). Note that RDRAM-based systems benefits MORE from overclocking than do DDR-based systems. They ue the extra memory bandwidth better.
It contains the Intel 850 chipset (supports only Rambus DRAM).
A large image of this board is posted here
(122KB, 820x580). Notice how the Rambus RAM RIMM slots are perpendicular
to each other. Some people feel that this perpendicular design limits
overclocking potential (no hard evidence, debatable point).
The Holy Grail of stable overclocking is achieved when you are able
to reach the next default FSB speed, with a motherboard that supports
the necessary AGP and PCI dividers, so that you can run those busses
at DEFAULT speeds.
Referring to the P4T-E's clock generator this thread contains more related info. Received a note from a reader who claims that Outside Loop is selling the P4T-E motherboard with the good clock generator .. along with pre-tested 1.6A's that are guaranteed for 2.13GHz. I would verify this with them, tho. I shot them an email and asked if they were familair with the clock generator issue. Their response:
Also note that Atacom
is selling boards specifically designated with the good (ICS) memory
clock generator chips, which allow you to run your RDRAM at PC1066 speeds
and above (if your RDRAM is good enough).
A word about voltage: Most people feel that increasing CPU vCore
voltage 10% over manufacturers default spec is safe, but that
anything more represents a gamble. If I can't get there with 15% extra,
I don't go. For a chip with a default voltage of 1.50v, adding 10% would
bring you to 1.65v. Note that your chip will run hotter with
more voltage, so don't crank it up any higher than you need. I use Prime95
(freeware) to test CPU stability.
Update 30march2002: I couldn't resist $600 performance for a
measly $134 any longer, so I upgraded my system to Northwood
1.6A (from Newegg) @ 2138 MHz, based on the Asus P4T-E (with ICS chips).
The most notable thing about this new system is it's stability. I've
long heard from Pentium4 friends, who claim how stable their systems
were. I can see now that it's true.
A quick check at Pricewatch shows that Atacom is selling the Asus P4T-E for US$155. They have *two* versions: one with audio & one without. The one with audio sells for $7 more. I just got off the phone with a guy at Atacom (ext. 100) who swears that he has this board in stock.
[Note: this is not an endorsement of Atacom. I'm merely showing that this board is available now. Atacom's resellerrating is posted here, and it's not very good.]
The Intel i850 chipset is configured for dual-channel Rambus DRAM RIMMs. Each channel contains 2 RIMM slots, for a total of 4 per motherboard. The dual-channel configuration means that you must install your Rambus memory modules in matched pairs. So you will need at least 2 sticks of RAM. All unpopulated RIMM slots must be filled with what are called Continuity RIMMs (because Rambus is a serial technology).
Update 22jan2002 - Received a note from Dylan Williams who writes to say he has both the Asus & Abit Rambus-based boards and prefers the Asus board:
The full message is posted
here. Worth reading. Despite what he says, I've heard a lot of good
things about the Abit board. See here
for benchmarks of related info. If you go with the Abit board, which
a lot of people seem to like, make sure you get one with the ICS
9212-13 memory clock generator, which is rated for 600mhz.
The older ICS 9212-03 memory clock generators are only rated
for 400mhz (bad for you).
An article at Tom's Hardware, titled Pentium
4, Over 3GHz (dated 17jan2002), indicates that it might be easier
to overclock DDR RAM (than RDRAM). A DDR-based Gigabyte
8IRXP motherboard was used to overclock a 2.2GHz Northwood to over
3GHz with water cooling.
If that's true, that would be a significant reason to take the DDR
route. I wish I could get some comparative data on relative system stability
between Rambus and DDR-based systems.
Far as RDRAM-based systems go, I heard that you have the best chance
of successful over-clocking with RIMMs manufactured by Samsung.
It should be noted that the P4 was designed with RDRAM in mind
.. and later adapted to DDR. That would give an advantage to RDRAM.
Update 03nov2001: I've received a mailbox full of responses to my comments about Rambus RAM. Admittedly, I haven't researched RDRAM very much. All I know is that it provides performance comparable to that of DDR RAM, yet costs significantly more.
I posted one such response. This particular reader makes compelling points, and includes a brief history of RAM development. At the very end, he suggests that the (Rambus) RAM may be responsible for the P4-platform's superior stability over Athlon-based systems (which ran DDR RAM).
Since I don't mind paying extra for stability, I found this especially interesting. I asked if he had any references or links to support his claims, but have not yet heard back from him. If you'd like to see what I'm talking about, see here => Rambus RAM.
These remainder of this page contains a folksy comparison (contrast)
between Rambus and DDR RAM. If you have no need for this info, skip
next (last) page for more info related to the Intel Northwood
The train (Rambus) is narrower, but moves along at a much faster rate (800MHz). Conversely, cars on the freeway (DDR) take up a much wider (data) path, but move along at a slower rate (266MHz). Both methods transfer roughly the same number of people (data) per unit time (bits/sec). Rambus RAM will transfer 3.2GB/s of data (1.6GB/s per channel times 2 channels).
3.2GB/sec is equivalent to transferring the data contained in 5 full CDs (650MB per CD) every second. That's roughly triple the bandwidth performance of my current system. Like the narrow, high-speed commuter train, Rambus RAM is only 16-bits (2-bytes) wide, but moves along at a higher clock-rate (800 MHz). DDR RAM is 64-bits (8 bytes) wide, but moves along more slowly (266MHz).
Both methods accomplish roughly the same performance, but each goes about it in a different way. DDR RAM moves more data each step (Hz), but steps along at a slower rate.
Narrow bus data transfers are known as serial. Wide bus data transfers are known as parallel. Each has its own set of pro's & con's. Parallel is more established. Serial seems to be becoming increasingly popular, and is supposedly less expensive to manufacture.
Perhaps it might be worth noting here that Rambus RAM modules, running at 800MHz, run at exactly twice the (clock) rate of the front side bus (FSB), which runs at an effective clock-rate of 400MHz. This is where the word synchronous comes in. This guide continues and concludes on the next page. Linkage below.