GA-MA790X-UD4P (PCI-E 16x crashes but PCI-E8x does not)

[Prof]

Gotcha. There will be a "surge" at power up, but running a game or benchmark will be the real test of a PSU`s ability to supply the power that it claims.

The thing is, now I have removed the GTX460, and stuck the HD4850 back in, the machine is stable. I can play games and run benchmarks OK, the GTX460 might draw a bit more power than the ATI card, but the difference is not huge, and certainly shouldn`t cause any problem for my 700W PSU (50amp 12v rail).

I`ve got the Corsair PSU, cheap Gigabyte MB and a Phenom II 250 CPU on the way. In other words, I should be able to pin the problem down with a little more component swapping. My money is on the MB being at fault. As I said earlier, the GTX460 has had a bit of a "thrashing" in a couple of other PCs (with the same drivers that I`ve used), and it didn`t lock up once. I`m thankful that the fault does appear often, rather than being intermittent, otherwise it would be a devil to sort out.

[Dark Mantis]

Your PSU should be fine if it is 700W, I don't know why but I thought it was much smaller for some reason. It could well be the motherboard but it is hard to tell at the moment. As you say it is easiest when you can just swap out components.

[Prof]

I have pretty well swapped everything (see my first post on the previous page).

I know my PSU (700 watt Coolermaster SilentPro) is more then enough for the job, but I`ve been into electronics for long enough to realise that nothing can be ruled out. Although I didn`t believe there was much chance of it being my PSU, I did run my new GTX460 in a friend`s PC with my PSU (which worked fine). I would have run my PC with my new GTX460 and another PSU, but neither of my friend`s PCs (which I happened to build) have a PSU with 2 x 12v supplies for the motherboard. My MA790X-UD3P has the 2 x 4pin 12v socket for CPU power, so I have not yet tried another PSU with my MB. Both RAM and CPU have been changed, but the GTX460 still won`t behave itself in my MB. It`s frustrating, because I have this nice new GFX card, but I can`t use it properly.

On another note, I emailed Gigabyte technical support at the weekend about this matter, still no reply. Do you know how long they take to respond ?

[Dark Mantis]

If it is dealt with at a local level it might only take a few days, however if it is answered by GGTS in Taiwan it could be ten days. And I am afraid to say none of them work at the weekend.

[Prof]

It is the motherboard.

The GA-M68M-S2P arrived today. I fitted it, installed Win 7, and now I can witness the power of my new graphics card.

I ran the Heaven benchmark, and for once it completed. I then left kombustor running for about 20 minutes, came back to the machine and it`s still running !

Earlier, I tried the GTX460 in the secondary PCIe slot (it`s x8 on my board). I believe that the card should run in the secondary socket, but a little slower. Well, it sort of worked, but the booting into Windows was very slow, the mouse pointer kept stopping, and one ore twice the machine crashed.

Anyway, at least I`ve now proved were the fault lies, the motherbard will be sent for repair.

[Dark Mantis]

I am glad you finally managed to prove the fault. At least now you can send it for RMA and get it sorted.