It supports it. Not explicitly mentioned in the manual, but take a look at page 3-3 BIOS Setup - there's a field for ECC Data Integrity Mode and an explanation that states that for ECC to work you need ECC RDRAM. Here's a review of the board where the reviewer used two PC800 ECC modules.

AFAIK, all i850 boards support ECC as it's a basic function of the i850 chipset.

Do note however that 1GB and/or registered modules won't work - the i850 supports max 512MB per DIMM, and they should not be registered.

Thanks a lot. On "my" version of the manual I do not have that mentioned, maybe you could upload "your" version so everybody can have it. I will order a pair of 256mb dimms and a pair of C-rimms and report how it all went!

Got it here:
https://www.manualslib.com/manual/599662/Abit … Th7ii-Raid.html
3-3 is page 29 in the viewer

RDRAM arrived and installed. I can report that it passed Memtest without errors which is great! The super great is the RAM is actually 2*512mb for a total of 1gb and not the 512mb in the original listing!
Now can I mix the original 2*256mb dimms which are not ECC with the 2*512mb ones which are ECC for a total of 1.5gb of RAM? I would try to install a Windows XP to see how it is running on a machine from 2002! Currently I have Windows ME installed - I know, I committed a cardinal sin 😀 - and it is running pretty well!

I had four of the MR18R162GAF0-CK8 modules in my board back in the day. I never tried mixing different kinds of memory. I imagine it will work, but ECC will be disabled on all modules.

From the performance point of view how is it better: ECC disabled or enabled? Does ECC impact performance? I ask because I never used ECC RAM before.

nd22 wrote on 2022-07-19, 07:42:

From the performance point of view how is it better: ECC disabled or enabled? Does ECC impact performance? I ask because I never used ECC RAM before.

Firstly, if you have ECC and non-ECC RIMMs mixed, you must disable ECC in BIOS.

But assuming you're running ECC-capable modules only, you can enable it. In that case it will not impact throughput, but will slightly impact memory latencies (by about 2%). In return, you get the additional data integritiy that ECC can offer, fixing single-bit-per-word errors and identifying double-bit ones. So it's not a performance feature but a reliability one. If you want the fastest possible system, leave it off. If you even suspect memory errors it's very useful to turn on.

I managed to find one hour of free time and installed XP SP3. The system is very responsive and fast, in fact Windows performance when working with files seems better: file copy is faster than under Windows ME; games installation times are lower.
I should mention the complete specs:
Pentium 4 2800 northwood FSB 400; Abit TH7II-raid; Samsung 2*512mb RDRAM PC800-400; Ati radeon 9700 pro; WD 120gb PATA, no name DVD-RW PATA, XP SP3 standard with no updates and not connected to the internet. Everything is running just fine, no crashes, no slowdowns. The hard disk is period correct however it is really slow - below 50mb/s sustained transfer rate!

I had a similar rig for most of the 2000s. I only chucked it in the end because the board blew a cap.

I come back today with a follow up to the story!
Managed to find another kit of 2*512mb Infineon modules and bought it. Arrived yesterday and installed. Memtest ran just fine. Tested some games and 3dmarks, however every single time the performance was good but not "up there". NFSHP2/Undying/C&C generals performance was average at MAX settings. I suspected from the outset that the video card is the culprit despite being ATI RADEON 9700pro, the most powerful GPU of 2002. Changed it to a 9800xt and performance jumped 50% in games and benchmarks. Further testing revealed that 2003 games can be run very well on this system and furthermore 128mb of video memory is not enough at MAX settings even in 2003 games. I decided to see if I can push the system to its limits and tested some DirectX 9.0 games from 2004. Half life 2 performed poorly with frames in the low 20's. Far cry 1 again brought the system to its knees with horrible stutters and deeps in the low teens so a new video card was installed: geforce 7800gs, the most powerful nvidia AGP video card. Again a huge jump in performance: 2004 games became playable.
One question remains: can the Pentium 4 3066mhz be used in this system? I am fully aware that only the intel 850E chipset is validated to run at FSB 1066 however most info on the net says that any board with intel 850 chipset should be compatible with the increased FSB without any changes.

I had a SL6S5 in my system. It runs at 533 MHz and has Hyper-Threading.

I installed the Pentium 4 3066mhz SL6PG. The system just booted up normally, no settings or anything to change in the BIOS was required. Now I can say I built the ultimate 2002 machine if I put back the radeon 9700 pro. However one problem is bugging me: how can I set the memory to PC1066? The only options available in the BIOS are 300 and 400; there is no 533 option available!