SOLVED: new psu - System reboots during gameplay after 7850 upgrade - PS?

jordanl17

Junior Member
Apr 22, 2007
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I have an Antec SP-500 ps, and have been using that with my system for years with a Radeon 4830 (oc'ed a bit). No problems playing games at all.
Last night I uinstalled at Catalyst/drivers, removed the 4830, and then installed the 7850, then the latest Catalyst. Went well.

Now randomly, but with a few minutes, my system reboots! no bluescreen, no entries in the Event Log.

I tried to reseat the 6pin PCI power.. I thought it helped... nope, still reboots.

I ran Prime95 for about 45 min, no problem. Heaven demo causes a reboot.

Thoughts?

I think the Antec SP-500 is bad, right? I'm going to get a SeaSonic M12II 620 Bronze 620W, as I am very sure it's a PS issue.
 
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Auric

Diamond Member
Oct 11, 1999
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According to reputable techpowerup reviews, average and peak power consumption of the 7850 is half as much as the 4830, and idle is one tenth. If more than one PCIe power plug, try the other. Otherwise it could be a mainboard/chipset/BIOS issue. Check for updates.
 

Termie

Diamond Member
Aug 17, 2005
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According to reputable techpowerup reviews, average and peak power consumption of the 7850 is half as much as the 4830, and idle is one tenth. If more than one PCIe power plug, try the other. Otherwise it could be a mainboard/chipset/BIOS issue. Check for updates.

That really isn't close to correct. The HD4850 uses about the same or slightly less power than a 7850 at load. While they are generations apart, we can use the delta versus a 5850 as a measure:

4850 vs. 5850 (-24w): http://www.anandtech.com/show/2848/13
7850 vs. 5850 (-14w): http://www.anandtech.com/show/5625/...-7850-review-rounding-out-southern-islands/17

Now, they are close enough that this shouldn't be a PSU issue, but that appears to be a pretty old PSU (introduced in 2005), so for a variety of reasons, it could be the culprit.

What's the motherboard/CPU, by the way? If it's old enough, it's not going to be entirely compatible with a 7850, as in older than PCI 2.0.
 
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jordanl17

Junior Member
Apr 22, 2007
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thanks for all the research, I should have looked up all the info myself. One quick note, the card is an oc'ed 4830 (so I guess compairing it a 4850 is correct).

To confirm it's not a physical connection issue I am going to remove the PCIe power from the card and run some benchmarks. I have a feeling I will get the same reboot issue.
thoughts?
what happens when there's no PCIe power in a card? my mobo is an H77 w/ PCI 3.0

thanks
 

Termie

Diamond Member
Aug 17, 2005
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thanks for all the research, I should have looked up all the info myself. One quick note, the card is an oc'ed 4830 (so I guess compairing it a 4850 is correct).

To confirm it's not a physical connection issue I am going to remove the PCIe power from the card and run some benchmarks. I have a feeling I will get the same reboot issue.
thoughts?
what happens when there's no PCIe power in a card? my mobo is an H77 w/ PCI 3.0

thanks

It won't run.

And it's not your motherboard, that's for sure. Just get a new PSU. Your system is due an upgrade.
 

Auric

Diamond Member
Oct 11, 1999
9,591
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That's weird if techpowerup is so off. Yeah, since not an older mainboard it is most likely the card itself or the PSU for whatever reason (since consumption is still lower). If you don't the mind cost it is a relatively easy troubleshooting step and may be a good idea anyway.
 
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SolMiester

Diamond Member
Dec 19, 2004
5,330
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Sounds exactly same symptoms i experienced when the PSU i once had, didnt have enough juice for the card and system....
You haven't listed the rest of your system, but I would have to say that its a power issue for sure.
 

cusideabelincoln

Diamond Member
Aug 3, 2008
3,275
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That's weird if techpowerup is so off. Yeah, since not an older mainboard it is most likely the card itself or the PSU for whatever reason (since consumption is still lower). If you don't the mind cost it is a relatively easy troubleshooting step and may be a good idea anyway.

They weren't off. Back when they tested the HD 4830 they tested power consumption at the wall and not at the video card like they do now.