I recently bought a new ASUS EAH5850 graphics board. I installed it a custom PC which had an ASUS p5n-e SLI mobo along with a 500w Thermaltake W0093RU power supply.
Sometimes when doing a cold boot the 5850's fan will run at full speed and the PC will not boot. Powering off by holding down the power button and powering back on sometimes remedies the situation and everything boots normally. Warm reboots also never seem to have problems. For some reason though cold boots almost always do. Another issue I notice is that when the PC does boot normally it takes longer (+30 secs) to POST than with my last video card. I flashed the mobo with the latest available BIOS but it had no effect.
Is my problem a power issue or incompatible motherboard or something else I'm missing?
Best Answer
It could easily be power related.
I can't find any specs for your ASUS card, but the AnandTech's review shows that the Radeon HD 5850 card is rated at about 151W which could be up to 12.58A off of the 12V power rail. Keeping in mind that high power cards need to charge up their capacitors when power is first applied, you could be in for a problem especially if you have more devices on your 12V power rail.
Your power supply has two 12V power rails. 12V1 has a max load of 14A and 12V2 has a max load of 15A. 12V1 supplies the main 24-pin power connector and the SATA power connectors. 12V2 supplies the PCIe power connector. Unfortunately, the users manual doesn't specify which rail the 12V comes from with the peripheral power connector and 2x2 power connector. If it is 12V1, you could be overloading the 12V1 power rail. The only way to know for sure is to measure the current draw, which is hard to do without a current probe or a current meter. An alternative is to try another power supply with two PCIe power connectors and more than two 12V power rails or 12V power rails with > 15A max current.
As far as the 30s to POST, it would be really nice if you had a POST card to figure out what POST code is displayed when it it pausing. This could be caused by the card having trouble powering up.
Also....