Well i have the heatsinks from the mac pro 2008 that I also got the processors from. They fit perfectly. Compatible with every matched pair of fbdimms? So it should have worked with pc4200f?
Yeah dual lga771 systems are awesome, just like all dual cpu boards but that is not the main reason why I decided to buy that board. I decided to buy it because I already had the xeons and thought that would be a pretty good value. I know more modern systems are more practical, but then I would also have to buy new processors and then I would have spare xeons and I wouldn't have peace until I stuck them somewhere 😁

It will work with pc2-4200f. Tested on my xw with 1066, 1333 FSB. Not sure with 1600FSB, these i haven't tested.
Dual lga771 is nice rig but performance of fbdimm is awful.

Callahan wrote:

It will work with pc2-4200f. Tested on my xw with 1066, 1333 FSB. Not sure with 1600FSB, these i haven't tested.
Dual lga771 is nice rig but performance of fbdimm is awful.

The performance of FBDIMM is not awful. It's a different technology that apparently you don't understand.
FBDIMM is server grade RAM. Server grade RAM is designed for low error rates vice raw speed.

The throughput might be slower on paper but it's of higher quality (less errors in it) so the CPU does not have to spend as much time repeating data transfers that were corrupted as it does on a computer with consumer based RAM.

FBDIMM is unlike previous technologies in that the ECC is internal (on the module only). It is not between the CPU and RAM.
That allows all the errors to be fixed 'in RAM' (which reduces CPU-RAM loading) and why it runs slower -on paper- than consumer RAM.
Consumer RAM might be faster -on paper- but it has the overhead of the CPU having to fix errors that would have been taken care of in RAM on a FBDIMM system.

IOW:
FBDIMM is slower with fewer errors that require repeating operations.
Consumer RAM is faster with more errors that require repeating operations.
At the end of the day there is no humanly perceivable difference between FBDIMM and consumer RAM of otherwise similar specs.

It seems hypocritical to me that you are criticizing FBDIMM performance at the same time you are recommending PC2-4200F which is the wrong spec RAM for the system and will underclock it by about 25%.
.

Skyscraper wrote:

Fast 4GB FB-DIMM modules are normally really expensive here in Sweden.

If you shop around on eBay US 4Gb FBDIMMs can easily be had for ~$7/module (shipped).
That's $1.75/Gb in 4Gb sticks. -- Compare that to 4Gb DDR3 modules.
.
I have no idea the situation on your side of the pond.
.

@OP.
You should look at your PSU load distribution.
Your total watts can be fine but you can at the same time have insufficient amps on one or some of your +12v rails.
.

PCBONEZ wrote:

If you shop around on eBay US 4Gb FBDIMMs can easily be had for ~$7/module (shipped). That's $1.75/Gb in 4Gb sticks. -- Compare […]
Show full quote

Skyscraper wrote:

Fast 4GB FB-DIMM modules are normally really expensive here in Sweden.

If you shop around on eBay US 4Gb FBDIMMs can easily be had for ~$7/module (shipped).
That's $1.75/Gb in 4Gb sticks. -- Compare that to 4Gb DDR3 modules.
.
I have no idea the situation on your side of the pond.
.

Ebay US sadly isnt a choice because of shipping + VAT + handeling fees.

I have payed ~$3 each for most of my 4GB DDR3 ECC REG sticks, I won 18 nice Samsung sticks in a single auction.

Skyscraper wrote:

PCBONEZ wrote:

If you shop around on eBay US 4Gb FBDIMMs can easily be had for ~$7/module (shipped). That's $1.75/Gb in 4Gb sticks. -- Compare […]
Show full quote

Skyscraper wrote:

Fast 4GB FB-DIMM modules are normally really expensive here in Sweden.

If you shop around on eBay US 4Gb FBDIMMs can easily be had for ~$7/module (shipped).
That's $1.75/Gb in 4Gb sticks. -- Compare that to 4Gb DDR3 modules.
.
I have no idea the situation on your side of the pond.
.

Ebay US sadly isnt a choice because of shipping + VAT + handeling fees.

I have payed ~$3 each for most of my 4GB DDR3 ECC REG sticks, I won 18 nice Samsung sticks in a single auction.

That's a good price.

The thing we run into in the US is that shipping from 2+ states over often costs more than to ship from overseas.
Sometimes the item + shipping is cheaper from overseas than just the shipping inside the US.
.

PCBONEZ wrote:

The performance of FBDIMM is not awful. It's a different technology that apparently you don't understand. FBDIMM is server grade […]
Show full quote

Callahan wrote:

It will work with pc2-4200f. Tested on my xw with 1066, 1333 FSB. Not sure with 1600FSB, these i haven't tested.
Dual lga771 is nice rig but performance of fbdimm is awful.

The performance of FBDIMM is not awful. It's a different technology that apparently you don't understand.
FBDIMM is server grade RAM. Server grade RAM is designed for low error rates vice raw speed.

The throughput might be slower on paper but it's of higher quality (less errors in it) so the CPU does not have to spend as much time repeating data transfers that were corrupted as it does on a computer with consumer based RAM.

FBDIMM is unlike previous technologies in that the ECC is internal (on the module only). It is not between the CPU and RAM.
That allows all the errors to be fixed 'in RAM' (which reduces CPU-RAM loading) and why it runs slower -on paper- than consumer RAM.
Consumer RAM might be faster -on paper- but it has the overhead of the CPU having to fix errors that would have been taken care of in RAM on a FBDIMM system.

IOW:
FBDIMM is slower with fewer errors that require repeating operations.
Consumer RAM is faster with more errors that require repeating operations.
At the end of the day there is no humanly perceivable difference between FBDIMM and consumer RAM of otherwise similar specs.

It seems hypocritical to me that you are criticizing FBDIMM performance at the same time you are recommending PC2-4200F which is the wrong spec RAM for the system and will underclock it by about 25%.
.

I don't recommend You pc2-4200f, i told You only that they will works. Nothing Else. i'm not using it for a few years.
I know how fully buffered dimms working, i know buffer for data and adress lines on modules. I know that motherboard using fdbimms is less complicated than unbuff - thanks to buffer on modules. I know how works ecc on that types of memory-here in adress and data lines. I'm using this workstations for years and i know that some types of work is slower than machine with same type (e5440 vs q9550) cpu with ddr2 unbuffered ram. Ram throughout is bottleneck with fbdimms. Only thanks to seaburg nothbridge cache and dual cpu mobo performance is awesome. FBdimms reminds me intel's dance with rdram... dead end.

Not really.
Memtest only shows you the speed of each module, not the total bandwidth.
Systems with DDR2 unbuffered ram can typically only take up to 4 modules.
FB-DIMM systems can hold up to 16 modules. Some may even take more.
Adding more modules has the same affect on total memory bandwidth as adding more lanes to PCIe.
Thus there is no bottleneck unless you don't know how to set up the system to avoid it.
.

Have you ever used a computer with fbdimms?
System with fbdimm can take more memory slots (even risers) thanks to less complicated pcb, due to the presence of a buffer on modules.

How to set up? Set up what? 8 memory slots, 8 identical samsung modules, each 4GB.
Seaburg is a quad channel 256bit NB, i know that.

Memtest showing nothing with fbdimms.
Good testing app is 7zip.

I like machines with fbdimm and rdram but they're not a speedsters.

Callahan wrote:

Have you ever used a computer with fbdimms? System with fbdimm can take more memory slots (even risers) thanks to less complicat […]
Show full quote

Have you ever used a computer with fbdimms?
System with fbdimm can take more memory slots (even risers) thanks to less complicated pcb, due to the presence of a buffer on modules.

How to set up? Set up what? 8 memory slots, 8 identical samsung modules, each 4GB.
Seaburg is a quad channel 256bit NB, i know that.

Memtest showing nothing with fbdimms.
Good testing app is 7zip.

I like machines with fbdimm and rdram but they're not a speedsters.

I've been using them for years.
My every day machine (the one I'm on right now) is a Supermicro dual Xeon socket 771. - Memtest runs on it just fine.
I repair them at component level too. Soldering iron, o'scope and all that. That's what I do.
I have an R&D dual skt 771 machine with 64GB of RAM in it as well. - Memtest runs on it just fine.
Also a Dell Precision 490 I never bothered to put to a use. - Memtest runs on that just fine too.
And something like 30 other dual Xeon boards in stock.
And probably something like 400-500Gb of FB-DIMM in stock.

When you suggest 7zip (a file compression program) for testing RAM it's clear you are clueless.
It's also clear in the other RAM post you just made but I will address that later.
.

Does it work at all? With my XW4600 motherboard, I discovered that it is very picky about power supplies, despite it being a single processor X38 motherboard - it's probably the start up time, but only one of my power supplies works with it, and annoyingly it's an older one. It starts up for a fraction of a second, then immediately shuts down if the PSU isn't one it approves of.