AT A CROSSROADS: STILL NEW TO "SLI"

[BonzaiDuck]

I'm sort of an oldster -- was careful with my wallet and skeptical that dual-gfx SLI performance enhancement, even for the type of casual gaming I want to do, was unnecessary.

But I decided to spring for two BFG 9600 GT (512) cards. I put these cards in an 680i system -- OK . . . It was a Striker Extreme -- the ASUS "love-hate" experience, but I have another Striker system -- takes a licking, keeps on ticking.

This time, I had an E8400 processor with BIOS update for the Penryn Wolfdale. I was running the system at 400 Ghz or 3.6 Ghz CPU speed with VISTA 64. I had left the NBCore voltage on "auto" and it was showing 1.52V. One day, I shut down the system, and trying to boot up the following day led to swapping parts to prove that the mobo had died. It's in for RMA -- no promises on how it comes back.

Now I have an eVGA 780i board --- this time, with an E8600 processor. And I only socketed one of the two 9600 GT's. The NB voltage at "auto" was 1.4V, and I was able to drop back and PRIME95/IntelBurntest-certify at 1.35V. I may try for lower. But I've been able to over-clock to 4 Ghz with CPU voltage within the stock range or 1.26V (1.30V "set"). It runs cool and sweet.

I'm at a crossroads for wondering whether to put the second BFG 9600 GT back in the system. I contemplate dropping the settings to stock levels; adding the second card and installing the SLI bridge-connector; then, looking for a new NB voltage as I attempt to reset the speeds back to my target level.

QUESTIONS:

I note that the 780i board implements PCI_E 2.0, while the 680i board used the older standard.

What differences should I expect with the second card? Would not the original over-clock settings apply, with only some variation in the Northbridge voltage requirement?

Have people had troubles with SLI configurations and over-clocks? Or shortened motherboard longevity?

I'm cautious -- any useful comments eagerly sought. I'm also going to stick a Hauppauge PVR-250 card into the system while I contemplate whether I need to eventually get a dual-digital/analog tuner to replace it.

Fact is, I've burned out motherboards with the same resulting symptoms and no over-clocking. It's silly-cone -- it happens.

 

[nitromullet]

What differences should I expect with the second card? Would not the original over-clock settings apply, with only some variation in the Northbridge voltage requirement?

SLI scales at about 30-80% depending on the game. Scaling shouldn't improve any on 780i vs. 680i with 9600GTs.

I assume you are talking about CPU OC here, not GPU... Installing the second card shouldn't have any affect on your CPU/FSB OC whatsoever. Of course, with video card OCing, you can only obtain the lowest common denominator between the two cards in SLI.

Have people had troubles with SLI configurations and over-clocks? Or shortened motherboard longevity?

Not that I'm aware of. From everything I've read, the reference 780i boards (EVGA/XFX) are much better boards then any of the Asus 780i boards. I was tempted to go with an Asus P5N-T Deluxe because they are relatively inexpensive, but the reviews scared me off.

As I understand it, you have to be a little bit cautious with the voltage on Penryn CPUs, as they apparently tend to degrade over time with increased voltages if they are too high. Currently, I'm running my quad core at 3.2 GHz (1600 FSB) at stock voltages, which is runs very solidly. My goal isn't to eek the very last ounce of performance out of this thing, but just to get some free MHz by tweaking a few things in the BIOS.

 

[BonzaiDuck]

Originally posted by: nitromullet

What differences should I expect with the second card? Would not the original over-clock settings apply, with only some variation in the Northbridge voltage requirement?

SLI scales at about 30-80% depending on the game. Scaling shouldn't improve any on 780i vs. 680i with 9600GTs.

I assume you are talking about CPU OC here, not GPU... Installing the second card shouldn't have any affect on your CPU/FSB OC whatsoever. Of course, with video card OCing, you can only obtain the lowest common denominator between the two cards in SLI.

Have people had troubles with SLI configurations and over-clocks? Or shortened motherboard longevity?

Not that I'm aware of. From everything I've read, the reference 780i boards (EVGA/XFX) are much better boards then any of the Asus 780i boards. I was tempted to go with an Asus P5N-T Deluxe because they are relatively inexpensive, but the reviews scared me off.

As I understand it, you have to be a little bit cautious with the voltage on Penryn CPUs, as they apparently tend to degrade over time with increased voltages if they are too high. Currently, I'm running my quad core at 3.2 GHz (1600 FSB) at stock voltages, which is runs very solidly. My goal isn't to eek the very last ounce of performance out of this thing, but just to get some free MHz by tweaking a few things in the BIOS.

That's about what I would do. With all of these C2D/C2Q processors, I would flirt with settings that required voltages in the upper range of "acceptable." That didn't last long before I was fishing for a self-imposed red-line that would leave the reported idle voltage no more than a few-hundredths above the spec on the retail box.

As I insinuated, I had an old INtel Pentium 2 "SE440BX" motherboard that went south after about 18 months. With those chipsets, you couldn't over-clock anything, and you didn't bother. But the symptoms were identical to this experience with my ASUS 680i board.

Luck-of-the-draw, I guess. We'll see whether the P_O_S I sent to them returns as a functioning P_O_S, or something more like the twin I have set up for my Q6600 system.

It seems that the worst risk to take with the Penryns involve the CPU_VTT/FSB voltage setting. Anandtech showed that going above 1.5V would kill the processor immediately, suggesting that 1.45V was an "at your own risk" threshold. Others have said "1.35V." Advice seems to be that with some boards, you can clock to 400 Mhz at 1.2V, and if problems develop, find the sweet-spot setting for the GTLrefV lines. But 1.3 is still a safe setting.

On the Penryns, the sane limit for CPU voltage seems to be below about 1.37V. I figure if I can get a 25 to 30% over-clock with a 1.30V setting that in turn results in a reported idle value of 1.26 or 1.27V, that's as far as I'm going to go.

Well -- I'm going to pop the second 9600 GT back into this system with the eVGA 780i and see what happens.

 

[BonzaiDuck]

Originally posted by: nitromullet

What differences should I expect with the second card? Would not the original over-clock settings apply, with only some variation in the Northbridge voltage requirement?

SLI scales at about 30-80% depending on the game. Scaling shouldn't improve any on 780i vs. 680i with 9600GTs.

I assume you are talking about CPU OC here, not GPU... Installing the second card shouldn't have any affect on your CPU/FSB OC whatsoever. Of course, with video card OCing, you can only obtain the lowest common denominator between the two cards in SLI.

Have people had troubles with SLI configurations and over-clocks? Or shortened motherboard longevity?

Not that I'm aware of. From everything I've read, the reference 780i boards (EVGA/XFX) are much better boards then any of the Asus 780i boards. I was tempted to go with an Asus P5N-T Deluxe because they are relatively inexpensive, but the reviews scared me off.

As I understand it, you have to be a little bit cautious with the voltage on Penryn CPUs, as they apparently tend to degrade over time with increased voltages if they are too high. Currently, I'm running my quad core at 3.2 GHz (1600 FSB) at stock voltages, which is runs very solidly. My goal isn't to eek the very last ounce of performance out of this thing, but just to get some free MHz by tweaking a few things in the BIOS.

Just a footnote here. I popped in the second graphics card, hooked up the SLI bridge and power-plug. I didn't bother to reset the OC settings. And no problem.

Somehow, though, it looks like my vDroop just drooped an extra thousandth-of-a-volt or two. But so far, re-running some stress tests, no problem with it. And the slightly lower voltage? At idle, it seems to show the identical voltage as before addition of the card.

I would agree that adding more equipment shouldn't matter, especially if the PSU is more than adequate. Superstition, imagination . . . . what you don't know for sure, you might worry about. . .