Have you tried raising the voltage (Vdimm) a bit?

PD2JK wrote on 2024-02-27, 09:40:

Have you tried raising the voltage (Vdimm) a bit?

Yes, so when running at 333MHz and 2-2-2-5 I had it set to 2.7v (shows as 2.8 in the ABIT tool for some reason), but also tried 2.8v with 400MHz and it still wouldn't POST. There's a thread on the Corsair forum here where they suggest using 2.75v for faster timings with these modules (I can only work in 0.1 increments).

Which mainboard? Since the memory controller resides on the northbridge, maybe it needs some extra voltage too.

Maybe it need some extra cooling as well. Northbridges can get quite hot.

Yeah quite possibly. It's an ABIT NF7-M, nForce 2. Stock cooler on the northbridge although I do have a new-in-box Thermaltake Blue Orb I could try at some point.

Are you using the integrated graphics? Maybe the IGP doesn't like the such tight timings. Try using discrete graphics.

Although your board has that +12V 4-pin CPU connector, the PSU can deliver enough juice on both +5V en +12V rails?

Already using a discrete card so it won't be the IGP causing trouble. PSU is a reasonably modern - well, 10 year old maybe - Corsair unit, 400W, but that's something to double check. 4-pin CPU connector is hooked up. The ABIT tool does complain about a low -5v value but I've ignored it because it shouldn't be that relevant on this kind of S462/AGP/PCI build?

Correct. Only some old/older/oldest (pick one) ISA cards use -5V. 😉

with any luck it will be happier with 400 at 1:1, also you can try changing individual timings (CL, RCD etc) to see which one is giving you grief

With the 3000+ chip installed I'm getting very similar results as to when I ran the 2500+ at 400MHz FSB - unstable in 3DMark, artifacting and eventual system freeze for most runs. It does this with 1 or two modules installed (i.e. to check if dual-channel is a problem).

With the memory at stock (slow) timings and 400MHz I've run Memtest successfully multiple times. I've also added a blower fan next to the graphics card (Ti4200) in case that's having trouble for some reason. The only way I can get it stable is dropping the memory FSB using the divider (basically my only option with that is 320MHz). Doing that I can improve the timings again and it's stable, although there is still some hitching in some of the 3DMark tests.

The takeaway so far is whatever settings I try, these memory modules do not like 400MHz despite that being what they're supposed to run at. And 400MHz/CL2 is a non-starter, again despite what the sticker says!

Do we think this is a memory problem, or an nForce2 problem, or an ABIT NF7-M problem, orrr.....?!

Also, slightly sad I can't increase the multi on my 3000+ chip. I'd read nForce2 boards often ignore the lock and I had no trouble using higher multis on the 2500+. Turns out my 2500+ is an early unlocked chip so that was a bad test, and the later locked 3000+ will not take more than 10.5 🙁

I vote voltage problem. This being old Abit I would look at voltage lines with a scope

Finally having some success with this, in so much as, it runs at the speeds it's supposed to 😁

The two things that got it across the line were disabling AGP Fast Writes and bumping the chipset voltage. It seems like AGP Fast Writes are usually a recipe for instability and weird issues anyway. I tried -0.1v on the chipset and it didn't quite make it into Windows, and then with +0.1v it's completely stable. I've got the memory set to 2.5-3-3-6 which is, as far as I can tell from old Corsair forum posts referencing these C2PT modules, the correct certified speed for AMD Socket 462 platforms (Intel would be good for 2-3-3-6). I've managed a run at 2-3-3-6 but there was weirdness in one of the tests. 2-3-3-8 ran ok but I'm wary of pushing my luck. The difference between CAS 2 and 2.5 seems to be just a few hundred points, which nobody is ever going to notice in the real world.

I've also bumped the memory up to 2.7v as recommended by Corsair, and upped the CPU voltage too since it seems to be a bit undervolted - at 1.7v it actually runs at around 1.66 which is on the money.

It's definitely got the makings of a nice fast system now 😀

Good to see some improvements. Congrats! 😁