Memory issues, need expert advice

Hi everyone, great forum. I figured this would be one of the best places to ask for help...

Ok this is my ageing setup:
P4 Northwood 2.0GHz
Asus P4S533 motherboard (SiS645DX chipset)
1x1024MB DDR333
350W PSU, generic but has served me well
other specs irrelevant to my problem.

The next part is all background info, so skip to the next paragraph if you don't want to read my crap
Previously I had a 256MB module of DDR266. Obviously this wasn't enough for today's computing needs so I bought a 1GB module. Replaced the 256, booted up no problems. Ran Memtest86...first problem. Memory bandwidth was detected as 1100MB/s. (mind you this is DDR333, theoretical max bandwidth of 1350MB/s) 955 errors detected within the first cycle of test. I thought 'well ok, let's run something else first to make sure'. Prime95's Torture Test crashed within 30 minutes. I couldn't play any games for more than 15 minutes without the system restarting. So I got the 1GB module replaced. (incidentally, my 256MB module refused to work from this point onwards. Computer refused to boot with it.) It may be worth noting that the guy who sold me the RAM warned me that some motherboards and chipsets have a problem with 1GB modules, and said that if the replaced module still doesn't work well then it's definitely a compatibility issue.

So I got the new module, but the stability problems were still there. I tried everything - loosening up the latency timings, playing around with the CPU/Memory multiplier. Then I decided to try increasing the DIMM voltage as a last resort. No BIOS option, so I used the jumper on the motherboard and set it to 2.7V. So far everything is quite stable. Keyword: quite. Naturally the next step was to go back to overclocking my system. The default FSB was 100, so I set it to 105. All good. This is where it starts to go downhill. At anything past 105, the system becomes unstable and I get random shutdowns. Now I know this isn't a CPU issue because with my old 256 RAM, I overclocked the FSB to 120 before (hence CPU 2.4GHz, DDR266 @ 320, default Vcore and VDIMM). Now for my questions:

1. Since it's almost certainly the RAM that is holding back the OCing, will it help to increase the voltage to 2.9V? (2.8V is not possible, the jumper only allows for 2.5, 2.7 or 2.9)
2. Will this endanger my RAM? (At 2.7V and during high activity, the aluminium heatsink on the RAM feels quite warm to the touch, but still very tolerable) I really don't want to fry something that cost me that much money.
3. Is it worth getting a different motherboard to see if it works fine?
4. CPU-Z detects my RAM timings as 2.5-3-3-7. However, in the BIOS it says 2.5-4-4-7. These timings are set by SPD, I have not changed them. So which is correct?

Any help/advice is much appreciated. Thanks.

how about geting 2x512 mb?

I would very much prefer to just work with what I have rather than buying new stuff.

What brand of ram is that gig? You can do a google search and possibly find out the default timings, so at least that might answer that one question for you. With respect to voltage, most ram can take 2.9v without issue, so you're not going to fry it.

Your board is capable of a 133fsb cpu, but your 2.0 is a 100 fsb, but should be able to do more than 105, so it is not in all likelyhood your problem, therefore, everything seems to point to the ram as the likely source of the issues. However, this ram is so underclocked at this stage that I would have to believe that lack of compatibility with your mobo might very well be your problem. Have you checked this out yet at Asus's site? Checking this ram out on another board, as you mentioned, might be a good way to determine if the ram is faulty or if it just won't play with your specific board.

Another possibility is that of heldover settings. Did you reset your BIOS back to Default or such before you inserted your new ram? You need to clear the BIOS, I believe, in order to have the spd pick up the new info so that might contribute to the difference in your reported timings. There may have been some other settings that should have been cleared and maybe weren't.

Hope you can get it worked out.

Thanks for that, Reefa_Madness. The RAM has a heatsink on it, so it's not possible to see the markings on the chips. However, I do remember the name Kingston being mentioned when I bought it. I went to Kingston's website and looked up the most likely modesl of RAM (ie. 1GB, DDR333, non-ECC, unbuffered) and my motherboard is in fact listed as one that will support them. However, I have heard that sometimes the RAM manufacturer may claim it is compliant with a particular motherboard when in reality it isn't 100% compliant. (and vice versa as well, for that matter.)

With regards to the BIOS - I updated it to the latest version after putting in the first 1GB module, and reset to default several times in the course of trying to get them to work. Furthermore, my previous RAM's timings were 2-3-3-7 as well. (Set by SPD, reported both in the BIOS and in CPU-Z) But it doesn't really matter, my main concern is the stability issues when overclocking. The latencies can be sorted out later on when everything is all right.

Anyway, I might just try upping the VDIMM to 2.9V and see what happens.

It has been a not too uncommon occurrance that a stick of ram would have troubles running, but when moved to a different slot, it cleared up. Have you moved your stick around and tried using the different DIMM slots, beginning with the one closest to the cpu and working out?

Hm I hadn't thought of that. I was always under the impression that the first DIMM slot always had to be occupied. Might give that a shot then. Thanks.